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Phase III-IV PlanMain\0203\Phase III/IV Plan (05/15/03) Project Number 0203 PHASE III/IV REMEDIAL ACTION AND REMEDY IMPLEMENTATION PLAN Former Staab’s Service Station 459, 480 & 492 Pleasant Street Northampton, MA 01060 RTN: 1-0705 May 2003 PENNEY ENGINEERING, INC ENVIRONMENTAL ENGINEERS & SCIENTISTS 125 HIGH STREET MANSFIELD, MA 02048 (508) 261-1288 FAX (508) 261-1208 www.PenneyEng.com PHASE III/IV REMEDIAL ACTION AND REMEDY IMPLEMENTATION PLAN May 2003 Former Staab’s Service Station 459, 480 & 492 Pleasant Street Northampton, MA 01060 RTN: 1-0705 Prepared For: PLEASANT JOURNEY USED CARS, INC 459 Pleasant Street Northampton, MA 02703 (413) 774-6559 Prepared By: PENNEY ENGINEERING, INC 125 High Street Mansfield, MA 02048 (508) 261-1288 LSP Who Prepared This Phase III/IV Remedial Action and Remedy Implementation Plan: Signature: ______________________ Ralph P. Penney, PE, LSP Title: President License Number: 7755 Seal Date: ___________________ PHASE III/IV REMEDIAL ACTION AND REMEDY IMPLEMENTATION PLAN Former Staab’s Service Station 459, 480 & 492 Pleasant Street, Northampton, MA 01060 TABLE OF CONTENTS PAGE 1.0 INTRODUCTION ................................................................................................................ 1 1.1 Description of the Site................................................................................................ 10 2.0 SITE HISTORY................................................................................................................... 11 2.1 History of Use at the Site........................................................................................... 11 2.2 Current Operations at the Site................................................................................... 11 3.0 PHYSICAL SITE CHARACTERISTICS ............................................................................. 12 3.1 Previous Assessment Activities................................................................................. 12 3.2 Additional Assessment Activities ............................................................................... 14 3.3 Hydrogeologic Characteristics................................................................................... 15 3.3.1 Topography and Bedrock Characteristics ....................................................... 15 3.3.2 Soil Characteristics.......................................................................................... 16 3.3.3 Groundwater Characteristics........................................................................... 16 4.0 ENVIRONMENTAL FATE AND TRANSPORT OF OIL/HAZARDOUS MATERIALS ...... 18 4.1 Evaluation of Oil/Hazardous Materials........................................................................ 18 4.2 Migration Pathways .................................................................................................... 20 5.0 NATURE AND EXTENT OF CONTAMINATION ............................................................... 21 5.1 Extent of Free-Phase Gasoline................................................................................... 22 5.2 Extent of Soil Contamination ...................................................................................... 22 5.3 Extent of Groundwater Contamination........................................................................ 22 6.0 SUMMARY OF RISK CHARACTERIZATION.................................................................... 22 6.1 Selection of Method.................................................................................................... 23 6.2 Nature and Extent of the Contamination and Contaminants of Concern .................... 23 6.3 Identification of Potential Human and Environmental Receptors................................ 23 TABLE OF CONTENTS (cont’d) PAGE 6.4 Identification and Site Activities and Uses .................................................................. 23 6.5 Identification of Exposure Points ................................................................................ 23 6.5.1 Soil.................................................................................................................. 24 6.5.2 Groundwater.................................................................................................... 24 6.6 Identification of Exposure Point Concentrations.......................................................... 24 6.6.1 Soil.................................................................................................................. 24 6.6.2 Groundwater.................................................................................................... 25 6.7 Identification of Exposure Pathways........................................................................... 26 6.8 Identification of Soil and Groundwater Categories...................................................... 26 6.9 Applicable Method One Cleanup Standards............................................................... 28 6.10 Comparison of Exposure Point Concentrations to the Method One Cleanup Standards ............................................................................... 28 6.11 Conclusions of Method One Risk Characterization ................................................... 29 6.12 Characterization of Risk to Safety ............................................................................. 29 7.0 SUMMARY OF SITE CONDITIONS THAT WARRANT REMEDIAL ACTIONS ................ 30 8.0 REMEDIAL ACTION PLAN ............................................................................................... 30 8.1 Identification and Evaluation of the Remedial Technologies....................................... 30 8.2 Initial Screening of the Most Applicable Remedial Alternatives.................................. 32 8.3 Detailed Evaluation of the Remedial Action Alternatives............................................ 36 8.4 Selected Remedial Action Alternative......................................................................... 39 8.5 Feasibility of Implementing the Selected Remedial Action Alternative....................... 40 9.0 REMEDY IMPLEMENTATION PLAN ................................................................................ 41 9.1 Relevant Contacts ...................................................................................................... 41 9.2 Design of the Selected Remedial Action Alternative................................................... 41 9.3 Required Permits and Licenses.................................................................................. 43 9.4 Health and Safety Procedures.................................................................................... 44 9.5 Additional Notification Requirements.......................................................................... 44 9.6 Imminent Hazard Evaluation...................................................................................... 44 9.7 Implementation Schedule........................................................................................... 44 9.8 Operation and Maintenance....................................................................................... 45 9.9 Monitoring Program.................................................................................................... 45 TABLE OF CONTENTS (cont’d) PAGE 10.0 PUBLIC INVOLVEMENT ................................................................................................... 47 FIGURES Locus Map BWSC Site Scoring Map Table One – Summary of 1998 Groundwater Results Table Two – Summary of Groundwater Results, April 25, 2002 Figure One – Groundwater Flow on October 11, 2000 Figure Two – Groundwater Flow on April 25, 2002 Figure Three – BTEX Plume on April 25, 2002 Figure Four – C5 – C8 Aliphatics Plume on April 25, 2002 A full-size Remedial Action Site Plan dated 4/21/03 and an Installation Plan dated 4/21/03 are included in the rear pocket APPENDICES Appendix A Completed Phase III Remedial Action and Phase IV Remedy Implementation Transmittal Form (BWSC-108) and Copy of December 9, 2002 Access Letter from Quickbeam Realty Trust Appendix B Laboratory Analysis Report for Groundwater Samples Collected by Penney Engineering on April 25, 2002 Appendix C Boring Logs, Well Data Sheets, and Groundwater Elevation Log Appendix D Copy of Public Notification Letter, the Building Permit, and our Contact List Page 1 PENNEY ENGINEERING, INC 1.0 INTRODUCTION On behalf of Pleasant Journey Used Cars, Inc, Penney Engineering, Inc is pleased to submit this combined Phase III Remedial Action Plan and Phase IV Remedy Implementation Plan to finally remediate the historic release of gasoline at the former Staab’s Service Station located at 459, 480, and 492 Pleasant Street in Northampton, MA (“the site”). The site is defined as the area containing significant concentrations of gasoline-related contaminants in the soil and the groundwater. The site is located at the intersection of Pleasant and Conz Streets, as shown on the Locus Map located in the Figures section. This Phase III/IV Plan is being submitted in response to Administrative Consent Order ACO-WE-03-3001 entered into by Pleasant Journey and the Department of Environmental Protection (“the DEP”) on February 27, 2003. The Plan is based upon our review of the available assessment reports that have been prepared for the site over the past 11 years, the limited groundwater sampling we conducted on April 25, 2002 and our visual inspection of the site. The properties at 459, 480 and 492 Pleasant Street were previously under common ownership and operated as a gasoline station until 1955 when Pleasant Street (Route 5) was constructed through the station. We have confirmed the continued presence of free-phase gasoline floating on the groundwater in the area of the former dispensers and underground storage tanks that were removed from 459 Pleasant Street in 1984; under the adjacent portion of Pleasant Street; and extending to the area of the former tanks directly across Pleasant Street at 480 Pleasant Street. We have also confirmed the continued presence of significant concentrations of dissolved gasoline contaminants in the groundwater over a larger area that are migrating to the southeast in the direction of the local groundwater flow. The conditions at the site warrant the implementation of remedial response actions. The information available in the assessment reports for remediation design was limited. A groundwater pump and treat system briefly operated at the site on August 8, 9 and 10, 2000. A small soil vapor extraction system (SVE) successfully operated at the site on an intermittent basis from August 7 until December 7, 2000 when it too had mechanical problems. Pleasant Street is a very active, four-lane State highway which restricts access to the contamination. We have evaluated the applicable remedial technologies and determined that the most appropriate alternative would include pumping the contaminated groundwater from one or two proposed recovery wells in order to first depress the groundwater table to allow a majority of the free-phase gasoline to be removed with automatic or manual skimming from inside the large diameter recovery wells. Based upon the available assessment information, the center of the free-phase gasoline and the dissolved plume appears to be located directly under Pleasant Street. An optional recovery well to be located Page 2 PENNEY ENGINEERING, INC at 480 Pleasant Street is being proposed to expedite the remediation. We are initially hoping to utilize the former product piping under Pleasant Street to pipe to the optional recovery well. If we cannot locate the piping or if it is not suitable, we shall request to install the proposed recovery well at 480 Pleasant Street and then request approval from the Massachusetts Highway Department to trench across Pleasant Street at a later date. The treatment equipment shall be housed in an enclosed trailer to be located adjacent to the sales office at Pleasant Journey on a concrete pad, enclosed by chainlink fence. The remainder of the treatment system shall be installed underground to prevent freezing and damage. The groundwater being pumped shall be treated through a biodiffuser with regenerative vapor phase carbon for air emission controls. The treated groundwater shall be recharged back into the ground upgradient of the contamination to promote flushing and biological remediation. Once a majority of the available free-phase gasoline is removed, a SVE system installed as two zones in the area of the former dispensers and the tanks at 459 Pleasant Street, and one optional zone at 480 Pleasant Street, shall be activated to remove the bound free-phase gasoline from the pore spaces of the dewatered saturation zone above the depressed groundwater table. Once the SVE system has removed the bound free-phase gasoline, the groundwater shall continue to be pumped, treated and discharged upgradient of the contamination until the dissolved gasoline contaminants are consistently reduced below the Method One GW-3 cleanup standards for four consecutive sampling quarters. Remedial additives may be periodically injected into the recharged groundwater. We have included detailed design plans of the proposed treatment systems in the rear pocket of this document. The treatment trailer has been fabricated and the installation of the system is scheduled for June 2003. We are currently monitoring the elevation of the groundwater table on a weekly basis in order to install the system with a minimum of dewatering. On May 1 and 2, 2003, the pre-cast structures for the recovery wells were delivered to the site. The former tanks at 480 Pleasant Street were reportedly for the original gasoline station, which had dispensers along Conz Street. Reportedly, Conz Street was previously known as Maple Street, the main route into the center of Northampton. We believe that the tanks may have actually been for a gasoline station with dispensers on the opposite or both sides of Pleasant Street. In 1984, Mr. Robert Kalish, the owner of Pleasant Journey, remembered seeing pipes that lead to the former dispensers at 459 Pleasant Street when the tanks at 480 Pleasant Street were being removed. There may still be tanks buried at 459 Pleasant Street that were used to supply the former dispensers along Conz (Maple) Street. In 1988, a wellpoint was installed at the car wash at 492 Pleasant Street to evaluate installing a supply well. Gasoline was detected in the groundwater pumped from the wellpoint. On June 14, Page 3 PENNEY ENGINEERING, INC 1988, the DEP was notified of a release at 492 Pleasant Street. Site Number 1-0462 was assigned. The gasoline was traced to the former tanks at 459 Pleasant Street, but no one was sure where the gasoline originated from. Monitoring wells were installed and up to 12 inches of free-phase gasoline was observed in three wells. Groundwater was encountered at a depth of eight to 10 feet. On October 23, 1989, the DEP was first notified of the gasoline release at 459 Pleasant Street based upon the findings presented in an August 30, 1989 report by the former Certified Engineering and Testing Company of Weymouth, MA. Site number 1-0705 was assigned and it later became the Release Tracking Number (RTN) for the site. On January 25, 1990, a Phase II Scope of Work for the site was received by the DEP. On January 21, 1994, a Settlement Agreement was entered into by the prior and current owners of the properties that comprised the site. The Agreement stated that Pleasant Journey Used Cars, Inc, Mr. Robert Kalish and his former partner, Mr. John Guillot, would remediate the gasoline contamination at 459 and 492 Pleasant Street. The owners of 492 Pleasant Street contributed $70,000 to a fund established to pay for the remediation. The estate of the former owner of the properties also contributed $98,000 to the fund. The former owner of 492 Pleasant Street contributed $2,000. Pleasant Journey Used Cars, Inc, Mr. Robert Kalish and Mr. John Guillot agreed to use the contributed monies to remediate the contamination and contribute any additional monies required for the remediation or refund any monies not used. Numerous investigations and limited remedial measures were conducted at the site. The remedial measures were limited to manual bailing of the free-phase gasoline from monitoring wells over ten years, the limited groundwater pump and treat system, and the SVE mentioned above and fully described below. On December 4, 1996, the site was recommended to be classified as a Tier II site by Cold Spring Environmental, Inc of Belchertown. On December 8, 1998, a Method Three Risk Characterization was prepared by O’Reilly, Talbot & Okun Associates, Inc of Springfield. It had determined that there was no significant risk associated with the remaining contamination at the site. On March 26, 1999, the Method Three Risk Characterization, a Phase II Report, and a Phase III Plan were submitted to the DEP by Environmental Compliance Services (ECS), Inc of Agawam. ECS stated that no significant risk was identified at the site at that time. The application of oxygen-releasing compounds and an Activity and Use Limitation were recommended as a permanent solution for the site. On June 8, 2000, free-phase gasoline was again discovered in wells MW-9 and VM-1 at thicknesses of 0.69 and 0.14 feet, respectively. On June 29, 2000, an Immediate Response Action (IRA) Plan was submitted to the DEP by Acadian Environmental of Page 4 PENNEY ENGINEERING, INC Springfield. The IRA Plan originally proposed the installation of a groundwater pump and treat system and a separate SVE system using vapor phase carbon. Bailing of the free- phase gasoline was again to be conducted at specific wells according to the IRA Plan. The groundwater was to be pumped through an oil/water separator and two, 500-lb canisters of aqueous phase carbon before being discharged into a storm drain. On September 1, 2000, the IRA Plan was modified for the SVE system to use a catalytic oxidizer instead of vapor phase carbon, presumably because of high concentrations of gasoline vapors being removed from the soil. According to a November 30, 2000 IRA Status Report by Acadian, the SVE system began operating on August 7, 2000. The pump and treat system only operated at 1.5 gpm from August 8 to 10, 2000 because of mechanical problems. The SVE system utilized an existing well and did not include a knockout drum. Reportedly, the SVE system operated intermittently from August 7, 2000 until it too experienced mechanical problems on December 7, 2000. The second, June 22, 2001 IRA Status Report by Acadian stated that a Falco Model #500 catalytic oxidizer had been used with the SVE system until the second week of December 2000. Reportedly, the oxidizer was damaged when liquid gasoline was drawn into it. Reportedly, Mr. Kalish paid to have the oxidizer repaired. After it was repaired he was told that a larger oxidizer was required which would require him to upgrade the electric service at Pleasant Journey. The SVE system remained idle until it was removed from the site on April 18, 2001. On January 29, 2002, the DEP issued a Notice of Noncompliance (NON) to Pleasant Journey for its failure to complete Comprehensive Response Actions at the site. The NON requested that a third IRA Status Report be submitted by March 29, 2002. The NON also requested that a Phase IV Plan be submitted by April 29, 2002. A Phase IV Plan was originally due by December 4, 1999. The December 4, 1996 Tier II classification for the site expired on December 3, 2001. No extension application was submitted 60 days prior to the expiration date. On March 12, 2002, we inspected the site. Five inches of free-phase gasoline was measured in monitoring well MW-9. The gasoline appeared weathered, but smelled fresh. On March 22, 2002, we were retained by Mr. Kalish to assume the responsibility for providing Licensed Site Professional (LSP) services for the site. We briefly reviewed the numerous assessment and status reports that have been prepared for the site. Reportedly, the properties comprising the site were previously owned and operated as a gasoline station by Mr. Carlton H. Staab and his parents from 1912 until 1955 when Pleasant Street (Route 5) Page 5 PENNEY ENGINEERING, INC was constructed through the station, as shown on Figure One located in the Figures section. A gasoline station continued to operate at 459 Pleasant Street until 1983 when the 21,280 square-foot commercial property was purchased by Pleasant Journey and converted to a retail, used automobile dealership. Reportedly in 1984, four underground gasoline tanks were removed from 459 Pleasant Street. The capacities of the tanks were 1,500, 3,000, 8,000, and 9,000 gallons. On March 28, 2002, we submitted a third IRA Status Report to the DEP and proposed conducting additional assessment activities as an IRA Modification. On April 25, 2002, we gauged and sampled 19 specific wells at the site. We also conducted limited indoor air screening in some of the surrounding buildings. We confirmed the continued presence of free-phase gasoline in the area of the former dispensers along Pleasant Street at 459 Pleasant Street and in the area of former gasoline tanks located directly across Pleasant Street at 480 Pleasant Street. We assumed that the two areas of free-phase gasoline were connected under the adjacent section of Pleasant Street. We also confirmed the continued presence of significant, dissolved gasoline contaminants in the groundwater over a larger area comprised of the properties located at 459, 480 and 492 Pleasant Street. Both contaminant conditions warranted the implementation of remedial response actions at the site. We did not identify a Critical Exposure Pathway or an Imminent Hazard based upon the available information and conversations with the DEP. After at least 19 years, the free-phase gasoline had not significantly migrated to the southeast, toward the Connecticut River. For the next few months we reviewed the available documents and evaluated a number of remedial options with Mr. Kalish. We found that the car wash property, at 492 Pleasant Street, was listed as a Tier IB default site with RTN: 1-0462, although ECS had reported that a Downgradient Property Status Submittal had been submitted for it. On April 8, 2002, Mr. Michael Scherer from the DEP was asked and stated that no Downgradient Property Status Submittal had been received for RTN: 1-0462. Mr. Scherer agreed to internally link the two sites under RTN: 1-0705. The groundwater at the site is classified as GW-3. Reportedly, there are no private water supply wells within 500 feet. Municipal drinking water is available along Pleasant Street. There are no occupied residences within 30 feet of the site. Reportedly, none of the surrounding buildings have basements. However, the DEP stated that the groundwater at the site should be classified as GW-2 and GW-3 in the January 29, 2002 NON. The gasoline-contaminated soil cannot be excavated because of space restrictions and because it extends under Pleasant Street. An Activity and Use Limitation is an acceptable remedial Page 6 PENNEY ENGINEERING, INC option for Pleasant Journey, but may not be acceptable to the other property owners. Reportedly, deadlines were missed for insurance coverage or reimbursement from the 21J Fund. The soil is reportedly outwash with a high permeability, but it is known to have a high silt content which reduces the permeability. No hydraulic conductivity testing has been conducted. The free-phase gasoline has not significantly migrated, indicating low permeability and a low hydraulic gradient. The groundwater has not been tested for dissolved iron or manganese. Sewer and storm water pipes run along Pleasant Street, but may not be preferential pathways because they may be bedded above the groundwater table. Reportedly, there may have been a problem with the prior storm water discharge from the treatment system installed by Acadian, so that a future discharge would not be approved by the EPA or the City of Northampton. We have prepared a more accurate plan of the site and adjacent properties. Our Remedial Action Site Plan has been drawn to scale and shows all the important features. It has been used to prepare more accurate figures of the site. Groundwater contours and contaminant plumes are shown as separate figures. We have also evaluated the presence of an Imminent Hazard, a Condition of Substantial Release Migration and the presence of a Critical Exposure Pathway. Limited indoor air monitoring was conducted. No one has reported smelling gasoline in their buildings. According to the June 29, 2000 IRA Plan by Acadian, a Condition of Substantial Release Migration did not exist at the site even though up to 0.69 feet of free-phase gasoline was observed floating on the groundwater. We have conducted a focused feasibility study of the applicable treatment technologies to remediate the contamination. The most applicable technologies have been used to develop at least three remedial alternatives. Each alternative has been evaluated in terms of costs, ability to be constructed, effectiveness, and safety. We have met with Mr. Kalish to discuss the three alternatives in order to select the best remedial alternative to effectively remediate the site. We have determined that the most appropriate alternative would include pumping the contaminated groundwater from one or two recovery wells and treating the water in a biodiffuser, with vapor phase carbon for air emission controls. Pumping the groundwater would depress the groundwater table in order to first allow a majority of the free-phase gasoline to be removed manually or with automatic skimmers from the large diameter recovery wells. Once a majority of the available free-phase gasoline is removed, a soil vapor extraction (SVE) system would be activated to remove the bound free-phase gasoline from the pore spaces of the dewatered saturation zone above the depressed groundwater table. Once the SVE system has removed the bound free-phase gasoline, the biodiffuser shall continue to operate to reduce the dissolved gasoline contaminants below the Method One Page 7 PENNEY ENGINEERING, INC GW-3 cleanup standards. The treated groundwater would continue to be discharged upgradient of the contamination to promote flushing and biological remediation. Remedial additives may be injected into the discharged groundwater. On November 13, 2002, the DEP issued a second Notice of Noncompliance to Pleasant Journey. The second NON requested that a fourth IRA Status Report or an IRA Completion Report be submitted for the site within 30 days. It also requested that a Tier II Extension Request or a Response Action Outcome (RAO) Statement be submitted for the site. On December 5, 2002, we sent a letter to Mr. Kalish explaining his regulatory options. We recommended that we close the IRA activities and proceed with the remediation of the site as a Comprehensive Response Action. We also described a proposed treatment system and included conceptual design plans. We suggested that he discuss the installation of a second recovery well with the owners of the property at 480 Pleasant Street in order to expedite the remediation. We requested that he seek their written authorization. On December 9, 2002, we submitted a letter to the DEP which acknowledged our receipt of the second NON, reported our on going efforts to design a treatment system for the site and provided notification that we would be submitting an IRA Completion Report before December 16, 2002. On December 10, 2002, we received written authorization to install a recovery well at 480 Pleasant Street from the owners. On December 12, 2002, we submitted a combined IRA Completion Report and Tier II Extension Request for the site to the DEP. The submission of the IRA Completion Report closed the June 29, 2000 IRA Plan submitted by Acadian. The Tier II Extension Request requested that the DEP grant two, one-year extensions of the Tier II classification. The two extensions were requested to allow a treatment system to be installed and Remedy Operation Status to be achieved before the extended Tier II classification expired again on December 3, 2003. On December 17, 2002, Mr. Scherer contacted us to say that he received our December 12, 2002 submission. He also stated that there were violations associated with prior Notices of Responsibility issued for the site. He wanted to have Pleasant Journey enter into an Administrative Consent Order (ACO) to eliminate the violations and specify completion dates for the required Comprehensive Response Actions. W e discussed completion dates with Mr. Scherer. He wanted to meet with Mr. Kalish. He also stated that the DEP can only issue the requested two, one-year Tier II classification extensions with an ACO. Page 8 PENNEY ENGINEERING, INC On December 23, 2002, we ordered an eight-foot by 16-foot enclosed trailer to house the treatment equipment. The earliest delivery date was February 28, 2003. On January 8, 2003, Mr. Kalish meet with Mr. Scherer at the DEP office in Springfield. Mr. Kalish agreed to enter into an ACO. On January 17, 2003, the DEP issued a draft ACO to Mr. Kalish and sent a copy to us. We reviewed the ACO and discussed our requested revisions with Mr. Kalish. Mr. Kalish had his attorney review the draft ACO and our revisions. On February 11, 2003, we faxed a markup of the draft ACO to Mr. Scherer showing our requested revisions. Later on February 11, Mr. Scherer called us to say that he had no problems with our revisions. He also answered our two questions that pertained to our ability to install the treatment system at the site while the Tier II Extension Request is being reviewed and if the two, one-year extensions could be written into the final ACO. Mr. Scherer stated that the installation could proceed and that the extensions would be written into the ACO. On February 11, the DEP issued an ACO that incorporated all our requested revisions. On February 15, 2003, we reviewed the ACO and advised Mr. Kalish to sign it. Reportedly, Mr. Kalish signed the ACO and mailed it back to Mr. Scherer. On February 27, 2003, the ACO was signed by Mr. Michael J. Gorski at the DEP and it became effective. In February 2003, we sent draft copies of our plans to local contractors for quotations to assist with the installation of the treatment system. On February 27, 2003, Mr. Mark Kalish measured the available space to construct a concrete pad for the treatment trailer between the Pleasant Journey office building and Fulton Avenue. There was not enough space for the required setbacks. On February 28, 2003, we met with Mr. Kalish to discuss the treatment system. Mr. Kalish offered to relocate all the cars from the eastern portion of his property during the installation. He also said that he would repave the entire area we would excavate to install the system. We discussed upgrading the electrical service, connecting a dialer from the system to one of his telephone lines and saving approximately $20,000 by not installing automatic skimmers to remove the gasoline from the recovery wells. Mr. Kalish preferred to manually bail the gasoline. On March 10, 2003, we received the requested equipment deposit from Mr. Kalish and proceeded to order the treatment equipment. On April 3, 2003, we met with Mr. Kalish to discuss our latest design plans. Mr. Kalish directed us to design a third SVE zone to be located at 480 Pleasant Street to expedite the remediation. Mr. Kalish also designated a staging area west of the tire shed for storing the pre-cast concrete structures for the recovery wells. Page 9 PENNEY ENGINEERING, INC On April 4, 2003, we contacted Mr. Matthew Pitoniak of Quickbeam Realty Trust to discuss installing the recovery well and third SVE zone at his 480 Pleasant Street property. Mr. Pitoniak was concerned that the installation would block his southern curb cut at the car wash so we agreed to relocate the recovery well to the south. We agreed to send him copies of our latest plans. We requested an accurate plan of his properties. On April 7, 2003, Mr. Pitoniak faxed us a sketch of the important features that he measured at his property. In April we setup charge accounts with local vendors. On April 17, 2003, we faxed a revised plan of Recovery Well RW-2 to Mr. Pitoniak for his approval and ordered the pre-cast concrete structures from Arrow Concrete Products of Granby, CT. On April 18, 2003, we met with the selected excavation contractor, Grant Brothers Associates of Mansfield, to discuss the installation of the treatment system. It was agreed to postpone the scheduled May 5, 2003 start date because of the unseasonably high groundwater table. A large manhole box would be used to reduce the need to conduct costly dewatering. We agreed to begin monitoring the elevation of the groundwater table on a weekly basis. On May 1 and 2, 2003, Arrow Concrete delivered the pre-cast concrete structures to the site. Pleasant Journey Used Cars, Inc has assumed the responsibility for conducting and implementing the Phase IV Remedy Implementation Plan in accordance with MGL c. 21E and the Massachusetts Contingency Plan. The name, address and telephone number of the contact person is: Mr. Robert P. Kalish, President PLEASANT JOURNEY USED CARS, INC 459 Pleasant Street Northampton, MA 01060 (413) 774-6559 The first seven sections of this Phase III/IV Plan summarize the findings of our limited April 25, 2002 gauging and sampling of specific monitoring wells; our review of the numerous reports prepared for the site; and a December 8, 1998 Method Three Risk Characterization prepared by O’Reilly, Talbot & Okun Associates, Inc of Springfield. Section 8.0 describes our evaluation of the applicable remedial technologies and the remedial alternatives. It also describes the selected remedial action alternative. Section 9.0 describes the design of the selected remedial action alternative. Section 10.0 describes the public notification process. Because the site is classified as Tier II DEP approval of the Phase III/IV Plan is not required. Page 10 PENNEY ENGINEERING, INC A Locus Map, a May 17, 2002 BWSC Site Scoring Map, Table One, a summary of the 1998 groundwater sampling results by ECS, Table Two, a summary of our April 25, 2002 groundwater sampling results, Figure One – Groundwater Flow on October 11, 2000, Figure Two – Groundwater Flow on April 25, 2002, Figure Three – BTEX Plume on April 25, 2002, and Figure Four – C5 – C8 Aliphatics Plume on April 25, 2002, are included in the Figures section. Appendix A includes a completed Phase III Remedial Action and Phase IV Remedy Implementation Transmittal Form and a copy of the December 9, 2002 authorization letter to install an optional recovery well a 480 Pleasant Street from Quickbeam Realty Trust. Appendix B includes a copy of the laboratory analysis report for the groundwater samples collected by Penney Engineering on April 25, 2002. Appendix C includes copies of the most pertinent Boring Logs, Well Data Sheets, and Groundwater Elevation Log. Appendix D includes copies of the public notification letter, the April 25, 2003 Building Permit and our Contact List. A full-size Remedial Action Site Plan dated April 21, 2003 and a Remedial Action Site Plan dated April 21, 2003 are included in the rear pocket. The plans are to be used for the construction of the treatment system. . 1.1 Description of the Site The site is located at 459, 480 and 492 Pleasant Street in Northampton, MA as shown on the Locus Map. The site has historically been used as a gasoline service station from 1912 until 1984. The immediate area is relatively flat. There are commercial businesses along Conz and Pleasant Streets. There are homes along Pleasant Street to the north of the site. Pleasant Street is a four-lane highway and part of State Route 5. It is the main route leading into the center of Northampton from the south. As shown on the Locus Map, there is an active railroad line located along the rear of 480 and 492 Pleasant Street. Reportedly, coal was transported by train and stored at properties along Pleasant Street. The Mill River flows from the area of the site into the Connecticut River located approximately one mile southeast of the site. According to the May 17, 2002 BWSC Site Scoring, the site is not located within an Interim Wellhead Protection Area, a Zone II or a mapped Potentially Productive Aquifer. Reportedly, there are no private water supply wells located within 500 feet of the site. Municipal drinking water is available along Pleasant Street. The depth to groundwater at the site ranges from eight to 10 feet. There are no occupied residences located within 30 feet of the site. The groundwater at the site is classified as GW-3. In the January 29, 2002 NON, the DEP stated that the groundwater at the site should be classified as GW-2 and GW-3. According to previous reports, the groundwater was classified as GW-1. Page 11 PENNEY ENGINEERING, INC 2.0 SITE HISTORY 2.1 History of Use at the Site A title search for the site was not conducted. Based upon the prior reports and the October 22, 2001 Warranty Deed, a list of the owners of the property at 459 Pleasant Street and the date of purchase is presented in Table One. The deeds have been recorded at the Hampshire County Registry of Deeds. TABLE ONE History of Ownership 459 Pleasant Street Date of Purchase Owner Book and Page Number Ralph T. Staab & Gretchen S. Belz April 26, 1965 Carlton H. Staab 1461/66 1983 Robert P. Kalish May 28, 1986 Robert P. Kalish & John Guillot 2730/231 October 22, 2001 Robert P. Kalish The site was reportedly used as a gasoline station. It was commonly known as Staab’s Gasoline Station from 1912 until 1983 when the property at 459 Pleasant Street was purchased by Mr. Kalish and Mr. Guillot to be used for selling used automobiles. The properties at 480 and 492 Pleasant Street were also sold to others. 2.2 Current Operations at the Site According to the March, 1999 Phase II Report by ECS, the area of the site is zoned for General Business. There are a number of businesses along Pleasant Street as previously reported. The properties within the site are occupied by Pleasant Journey Used Cars, Pro Lube, a car wash, and an office building. Reportedly, there are no longer any underground gasoline storage tanks at the site. Automobiles are still serviced in the two-bay garage at Pleasant Journey and at Pro Lube. Sewer, water, and natural gas are available along Pleasant Street. Page 12 PENNEY ENGINEERING, INC 3.0 PHYSICAL SITE CHARACTERISTICS 3.1 Previous Assessment Activities In 1988, a wellpoint was installed at 492 Pleasant Street and gasoline was detected in the groundwater. On October 23, 1989, the DEP was first notified of the gasoline release at 459 Pleasant Street based upon the findings in an August 30, 1989 report by the former Certified Engineering and Testing Company of Weymouth, MA. Site number 1-0705 was assigned and it later became the Release Tracking Number (RTN) for the site. Numerous investigations and limited remedial measures were conducted at the site. On November 30, 1989, Certified submitted a Phase I Limited Site Investigation Report for the site. On November 8, 1993, an Interim Phase I Report was prepared by Cold Spring Environmental, Inc. of Belchertown, MA. In December 1996, a Phase I Completion Report and Tier Classification for the site were submitted by Cold Spring. Previous reports had also been submitted for 492 Pleasant Street. On December 8, 1998, a Method Three Risk Characterization was prepared by O’Reilly, Talbot & Okun Associates, Inc of Springfield. It had determined that there was no significant risk associated with the remaining contamination at the site. On March 26, 1999, a Phase II Report and a Phase III Plan were submitted to the DEP by Environmental Compliance Services (ECS), Inc of Agawam. ECS had conducted a Phase II Comprehensive Site Assessment at the site to determine the nature and the extent of the soil and groundwater contamination in order to evaluate risk. In 1997, they advanced 25 additional soil borings and installed five additional monitoring wells. Copies of selected Boring Logs and Well Data Sheets from the Phase II Report and prior reports are included in Appendix C. The location of all the borings and wells are shown on the four figures and the Remedial Action Site Plan. The names of the wells have changed over the years. During the advancement of the borings ECS conducted headspace screening of the split-spoon samples with an HNu Model 101 photoionizing detector setup with a 10.2 eV lamp and calibrated to read as benzene. The Model 101 was known to produce false readings for wet soil samples. The readings were recorded on their Boring Logs which are all included in Appendix B. The highest, or most representative, headspace readings are shown on the Remedial Action Site Plan for each soil boring. Based upon the headspace results, the soil contamination extends from the office at Pleasant Journey to the rear of the office building at 492 Pleasant Street. Based upon the headspace results, only one soil sample from 18 soil borings advanced on June 25, Page 13 PENNEY ENGINEERING, INC 1997 was analyzed for volatile organic compounds (VOCs) by EPA Method 8020. The single sample was collected from a depth of 12 to 13 feet from boring SB-4 located adjacent to the northeastern corner of the former dispenser pad at 459 Pleasant Street. Two other soil samples were reportedly analyzed for “hazardous waste treatability”, but no results or laboratory reports were reported. The results for the one soil sample analyzed included benzene at 43.5 mg/kg; toluene at 363.5 mg/kg; ethylbenzene at 116.5 mg/kg; xylenes at 555.0 mg/kg and methyl-tert-butylether (MTBE) at 5.8 mg/kg. We assumed that the most contaminated soil sample was analyzed. Clearly the results were above the Method One S- 1/GW-3 cleanup standards. We do not understand why only one soil sample was analyzed or why the results were expressed by mg/kg in the laboratory report. On April 2, 1998, ECS collected groundwater samples from 19 wells at the site. Specific samples were analyzed for volatile aromatic compounds by EPA Method 602, a method for analyzing drinking water; volatile petroleum hydrocarbons (VPHs); and extractable petroleum hydrocarbons (EPSs) with target polynuclear aromatic hydrocarbons (PAHs) by the new DEP method. On July 9, 1998 two groundwater samples were collected from the Shell station at 506 Pleasant Street along with another sample from 492 Pleasant Street. Reportedly, the samples were collected with dedicated, stainless steel bailers which are very expensive. On July 9, 1998, additional groundwater samples were collected from 491 Pleasant Street with a geoprobe. All the previous and 1998 groundwater sampling results were listed in three large tables. We have presented the most recent 1998 VPH results for specific wells and the GW- 2 and GW-3 cleanup standards in Table One included in the Figures Section. As shown in bold in Table One, a number of the wells contained dissolved gasoline-related compounds that exceeded the GW-3 cleanup standards. The significant contamination extended from 459 Pleasant Street to MW-12 across Pleasant Street. ECS did not report any free-phase gasoline in any of the wells they sampled. ECS stated that no significant risk was identified at the site in 1998. The application of oxygen-releasing compounds and an Activity and Use Limitation were recommended as a permanent solution. On June 8, 2000, free-phase gasoline was again discovered in wells MW-9 and VM-1 at thickness of 0.69 and 0.14 feet, respectively. On June 29, 2000, an Immediate Response Action (IRA) Plan was submitted to the DEP by Acadian Environmental of Springfield. The IRA Plan originally proposed the installation of a groundwater pump and treat system and a separate SVE system using vapor phase carbon. Bailing of the free-phase gasoline was to Page 14 PENNEY ENGINEERING, INC be conducted at specific wells according to the IRA Plan. The groundwater was to be pumped through an oil/water separator and two, 500-lb canisters of aqueous phase carbon before being discharged into a storm drain. On September 1, 2000, the IRA Plan was modified for the SVE system to use a catalytic oxidizer instead of vapor phase carbon. According to a November 30, 2000 IRA Status Report by Acadian, the SVE system began operating on August 7, 2000. The pump and treat system only operated at 1.5 gpm from August 8 to 10, 2000 because of mechanical problems. Reportedly, the SVE system operated intermittently from August 7, 2000 until it experienced mechanical problems on December 7, 2000. 3.2 Additional Assessment Activities On March 12, 2002, Mr. Ralph Penney from Penney Engineering met with Mr. Kalish to inspect the site. A few of the wells at 459 Pleasant Street were gauged and inspected. Five inches of free-phase gasoline was measured in a bailer from MW-9. It was apparent that remedial response measures were warranted. On April 25, 2002, we attempted to locate all the monitoring wells at the site. We were able to inspect and gauge 19 wells. The wells were gauged for depth to water and for the presence of free-phase gasoline with a Solinst interface probe. Free-phase gasoline was measured with the probe and confirmed with a bailer in wells MW-9 and MW-12. Distinct petroleum sheens and/or a strong petroleum odor were observed in the groundwater samples from wells MW-1, 4, 5, 6, 8, 10, 2A, 4CW, ECS-1, and ECS-5. We collected 14 groundwater samples from wells MW-1, 3, 4, 5, 6, 7, 8, 9, 2A, 8, 12, ECS-1 and ECS-5 in order to determine the extent of the dissolved gasoline contamination in the groundwater. A sample was also collected from well Bridal 447 as requested by Mr. Scherer. The locations of the wells are shown on Figures Three and Four. Samples could not be collected from MW-2, MW-10 and VM-1. Ten of the groundwater samples were collected according to DEP procedures and transported to RI Analytical, Inc of Warwick, RI under chain-of-custody protocol for analysis. The samples from MW-9 and MW-12 were not analyzed because they contained free-phase gasoline. The sample from MW-4 was not analyzed because it was located in close proximity to MW-5, 7 and 9. The 10 samples were analyzed for VPHs by the DEP method. The results for the compounds detected are summarized and compared to the GW-2 and GW-3 cleanup standards in Table Two located in the Figures section. The results that exceed the GW-3 cleanup standards are shown in bold. A copy of the laboratory analysis report is included in Appendix B. Page 15 PENNEY ENGINEERING, INC The results listed in Table Two are very similar to the 1998 ECS results listed in Table One. As shown in bold in Table Two, a number of gasoline-related contaminants were detected above the GW-3 cleanup standards. The detection limits on the most contaminated samples were high because of the relatively high concentrations of dissolved gasoline-related contaminants in the samples. We have attempted to determine the extent of the dissolved gasoline contaminants by plotting the results on Figures Three and Four. The iso-contours of the BTEX compounds are plotted on Figure Three. The iso-contours for the C5-C8 aliphatics fraction are plotted on Figure Four. We also attempted to show the extent of the free-phase gasoline based upon our April 25, 2002 gauging and previous reports of free-phase gasoline. The former dispenser area at 459 Pleasant Street has been reported as the most likely source of the gasoline release. Both figures show that the dissolved gasoline contaminants in the groundwater generally coincides with the estimated extent of free-phase gasoline as it migrates to the east with the local groundwater flow. We have not collected any soil samples. Only soil boring samples have been analyzed during previous assessments. Gasoline contaminants were detected in soil boring samples collected at or above the groundwater table. No soil samples were collected from beneath Pleasant Street due to access restrictions. No test pitting has been conducted at the site. We have assumed that the extent of the soil contamination is within the free-phase gasoline floating on the groundwater as shown on Figure Three. On April 25, 2002 we also conducted limited indoor air screening with an organic vapor meter setup with a 10.6 eV lamp and calibrated with isobutylene to read “as benzene”. We were allowed to conduct screening in the office and the garage at Pleasant Journey; the office and garage areas at Pro Lube; the car wash; the Sheriff’s Department office; the Community Corrections office; the Community Development office and the pet store. We were not allowed to screen the 591 Food Stop restaurant. None of the buildings had basements. No significant readings were recorded. The highest reading of 3.1 ppm was recorded in the pet store. 3.3 Hydrogeologic Characteristics 3.3.1 Topography and Bedrock Characteristics The site is located in the Connecticut River Plain. The area is relatively flat. There are no visible bedrock outcrops and bedrock was not encountered during the advancement of any soil borings. The depth to bedrock has been estimated to be 120 to 170 feet. It is know to be New Haven Arkose, a sandstone, according to ECS. Page 16 PENNEY ENGINEERING, INC 3.3.2 Soil Characteristics According to the Phase II Report by ECS, the soil at the site is Hadley-Winooski associated soils and Hinckley loamy sands. According to the numerous boring logs included in Appendix C, the soil at site is: 0-2 feet of asphalt, fill, ash, fine to medium sand; 2-7 feet of fine sand and silt; 7-12 feet of medium to fine sand, silt, trace coarse sand; and 12-16 feet of medium to coarse sand. A soil profile is included on the Remedial Action Site Plan. The groundwater is at a depth of approximately eight to 10 feet. The medium to coarse sand at 14 to 16 feet is expected to be of relatively high hydraulic conductivity to allow significant groundwater flow, however, the Connecticut River Plain is know to contain silt which restricts groundwater flow. 3.3.3 Groundwater Characteristics On April 25, 2002 we measured the depths to groundwater in 19 wells and used the data to calculate the groundwater elevations presented in Table Three. The elevations of the risers were surveyed and reported by ECS. Page 17 PENNEY ENGINEERING, INC TABLE THREE Groundwater Elevation Data April 25, 2002 Well Location Top of Riser Elevation (ft) Depth to Groundwater (ft) Groundwater Elevation (ft) MW-1 98.67 8.65 90.02 MW-2 99.64 9.46 90.18 MW-3 99.52 9.32 90.20 MW-4 NA 8.56 NA MW-5 99.01 9.04 89.97 MW-6 98.87 8.75 90.12 MW-7 98.81 8.92 89.89 MW-8 98.81 8.96 89.85 MW-9 99.03 8.98 0.47’ Gasoline MW-10 98.24 8.23 90.01 MW-12 99.02 9.12 0.05’ Gasoline VM-1 98.80 8.84 89.96 Bridal 447 NA 8.20 NA MW-2A 98.58 8.79 89.79 MW-1CW NA 9.36 NA MW-4CW NA 9.83 NA ECS-1 99.15 9.41 89.74 ECS-2 NA 9.60 NA ECS-5 99.03 9.21 89.82 NA – Not Available On June 8, August 2, October 11, 2000 and April 4 and April 18, 2001, Acadian had also measured the depths to groundwater and determined the elevation of the groundwater at specific wells. The results were reported in their June 22, 2001 IRA Status Report. We have plotted the groundwater contours based upon the fall, October 11, 2000 results on Figure One. As shown, the local groundwater flow direction is to the east, toward the Mill River which flows into the Connecticut River. We have also plotted the groundwater contours based upon our spring, April 25, 2002 results on Figure Two. As shown, the local groundwater flow direction is also to the east. ECS had also reported the flow to the east. The direction of the local groundwater flow is dependent upon the stage of the Connecticut River. Page 18 PENNEY ENGINEERING, INC 4.0 ENVIRONMENTAL FATE AND TRANSPORT OF OIL/HAZARDOUS MATERIALS 4.1 Evaluation of Oil/Hazardous Materials The contaminants of concern at the site are associated with gasoline, a petroleum product. This section presents a full description and evaluation of the contaminants of concern at the site. Benzene: C6H6 Synonyms: Benzol, phenyl hydride, benzole Chemical and physical properties: Colorless liquid; m.w. 78.11; SpG 0.879 @ 20°C; m.p. 5.5°C; b.p. 80.1°C; v.p. 76 mm at 20°C; solub. 1,780 mg/l at 20°C; sat. conc. 319 g/cu m at 20°C; log Poct 2.13 at 20°C; Henry’s Constant 230 atm. Benzene is used in the manufacture of organic chemicals and pesticides, plastics, resins, paints and coatings. It is a constituent of gasoline. Benzene is considered an occupational carcinogen by NIOSH. If benzene is released to the soil, it will volatize and leach into the groundwater due to its low to moderate adsorption to mineral soil. It will slowly biodegrade in soil and groundwater. Toluene: C6H5CH3 Synonyms: Methylbenzene, methylbenzol, toluol Chemical and physical properties: Colorless liquid; m.w. 92.1; m.p. -95.1°C; b.p. 110.8°C; v.p. 22 mm at 20°C; v.d. 3.14; SpG 0.867 at 20°C; solub. 515 mg/l at 20°C; sat. conc. 110 g/cu m at 20°C; Henry’s Law Constant 6.7 x 10-3 atm-m3/mole or 217 atm. Toluene is derived from petroleum distillation and is used in the manufacture of benzene derivatives and dyes, as a solvent for adhesives, paints and coatings, and is a component of gasoline. If toluene is released to soil, it will be lost by evaporation from near surface soil and by microbial degradation. Since it is relatively mobile in soil, it may leach into the groundwater where slow biodegradation may occur. Ethylbenzene: CH3CH2C6H5 Synonyms: Phenylethane, ethybenzol Page 19 PENNEY ENGINEERING, INC Chemical and physical properties: Colorless liquid; m.w. 106.17; m.p. -94.97°C; b.p. 132.2°C; v.p. 7 mm at 20°C; v.d. 3.66; SpG 0.867 at 20°C; solub. 152 mg/l at 20°C; sat. conc. 40 g/cu m at 20°C; Henry’s Law Constant 8.44 x 10-3 atm-m3/mole or 359 atm. Ethylbenzene is a petroleum derivative used in the manufacture of stryene, as a solvent, and is a major constituent of gasoline. When released to the soil, some evaporation may take place from near the surface. It is moderately adsorbed by soil but will leach into groundwater, especially in soil with a low organic carbon content. It will slowly biodegrade in groundwater. Xylenes (o-, m-, p- isomers): C6H4(CH3)2 Synonyms: Dimethylbenzene, methyltoluene, xylol Chemical and physical properties: Colorless liquid; m.w. 106.16; m.p. -25°C; b.p. 144.4°C; v.p. 5 mm at 20°C; v.d. 3.7; Sp G 0.88 at 20°C; solub. 175 mg/l at 20°C; sat. conc. 29 g/cu m at 20°C; Henry’s Law Constant 5.27 x 10-3 atm-m3/mole or 266 atm. Xylenes are used as solvents for resins, lacquers, enamels and rubber cements in the manufacture of dyes and insecticides. They are a major constituent of gasoline. Natural sources include coal tar, petroleum, forest fires, and plant volatiles. When spilled on soil, xylenes will volatilize and leach into the groundwater due to their low to moderate adsorption to soil. They will slowly biodegrade in soil and groundwater. Methy tert-butyl ether: (CH3)3COCH3 Synonyms: MTBE Chemical and physical properties: Colorless liquid with a disagreeable odor; m.w. 88.2; b.p. 5.5°C; v.p. 245 mm at 20°C; solub. 43,000 mg/l at 20°C; SpG 0.741 at 20°C; log Poct 1.1 at 20°C. Since 1978, MTBE has been used as an octane booster in unleaded gasoline. It can be present at up to 15 percent by volume in gasoline blends. MTBE is very soluble in water and has a low potential for adsorption to soil. It is generally the most mobile groundwater contaminant in releases of gasoline. Acute effects of exposure to MTBE may include skin, eye and nasal irritation. The use of the MTBE is currently being re-evaluated by the EPA. Page 20 PENNEY ENGINEERING, INC Volatile Petroleum Hydrocarbons: The VPH constituents are separated into three fractions as the C5-C8 aliphatic hydrocarbons, C9-C12 aliphatic hydrocarbons and C9-C10 aromatic hydrocarbons. The fractions represent the lighter petroleum compounds primarily associated with gasoline. The Method One cleanup standards for VPH were developed using conservative site scenarios to evaluate risks to human health, public welfare and the environment via exposure pathways such as direct contact, ingestion and volatilization. 4.2 Migration Pathways The free-phase and dissolved gasoline detected at the site may potentially migrate through the vadose zone and escape to the atmosphere. However, based on the localized area of groundwater contamination and the low permeability of the shallow soil above the groundwater table, it is unlikely that the contamination shall result in detectable concentrations of VOCs in the air at the site. Nothing was detected during our limited indoor air screening. In 1984 and 1988, a majority of the contaminated soil was removed from the former tank areas at the site. Free-phase gasoline remains in the area of the former dispensers at 459 Pleasant Street and across Pleasant Street at 480 and 492 Pleasant Street. The potential for the migration of any gasoline in the soil through the air by wind erosion is insignificant. The gasoline contamination shall continue to migrate with the groundwater to the east. The migration of the contamination in the upper portion of the aquifer may not be influenced by underground utilities because the utilities are probably bedded above the groundwater table. The groundwater at the site and in the vicinity is not reportedly used as a drinking water source. Therefore, exposure by ingestion of the groundwater is not a potential pathway. The groundwater velocity was estimated in an effort to characterize the groundwater as a potential migration pathway. Based upon variable-head slug tests conducted by ECS, the hydraulic conductivity (K) was estimated to be 6.41 feet per day. According to Darcy’s Law, the estimated K value, the hydraulic gradient measured between wells and an assumed porosity were used to calculate an estimated groundwater velocity across the site. The formula is presented below: Page 21 PENNEY ENGINEERING, INC Darcy’s Law V=KI/N Where V=velocity (ft/day) K=hydraulic conductivity I=hydraulic gradient (ft/ft) N=porosity The hydraulic gradient on April 25, 2002 was calculated to be 0.003 ft/ft between wells MW- 2A and 5, which are 156 feet apart. The soil porosity was estimated using typical values for gravelly, silty sand. The porosity was estimated to be 0.28. The annual velocity of the groundwater across the site is calculated as follows: V=[(6.41 ft/day) x (0.003 ft/ft) /0.28] x (365 days) V= 0.0002 ft/year The calculated annual groundwater velocity is very low due to the low hydraulic gradient. It is less than the Condition of Substantial Release Migration threshold of 200 feet per year. Although free-phase gasoline has been detected floating on the groundwater, there have been no reported releases of gasoline to the ground surface. The contaminated groundwater is not expected to affect any public or private water supply wells. All the known tanks have been removed from the site in the 1980s. The free-phase gasoline continues to remain in the area between the former dispensers along Pleasant Street and the former tanks at 480 Pleasant Street. There have been no recent releases to the groundwater reported. Vapors are not expected to discharge into any basements. No one has reported gasoline odors in their buildings. A Condition of Substantial Release Migration, as defined in Section 40.0006 of the MCP, has not been identified at the site. 5.0 NATURE AND EXTENT OF CONTAMINATION Figures Three and Four clearly show our estimated extent of the free-phase and dissolved gasoline contamination in the groundwater based upon our April 25, 2002 sampling results. Previous reports have identified a similar extent. The presence of the free-phase gasoline has not been consistently reported. In 1998, no free-phase gasoline was observed and the site was to be closed. However, on June 8, 2002, free-phase gasoline was again observed in wells MW-9 and VM-1 at 0.69 and 0.14 feet, respectively. Page 22 PENNEY ENGINEERING, INC 5.1 Extent of Free-Phase Gasoline Our estimated extent of the free-phase gasoline is shown as NAPL on Figures Three and Four. Our estimate is based upon previous reports of free-phase gasoline in specific wells and our April 25, 2002 observation of free-phase gasoline in wells MW-9 and MW-12. The presence of free-phase gasoline is associated with the height of the groundwater table. We have assumed that it extends under Pleasant Street. 5.2 Extent of Soil Contamination We assume that the extent of the gasoline contamination in the soil is similar to the extent of the free-phase gasoline shown in Figures Three and Four. Reportedly, contaminated soil was removed in 1984 when the underground storage tanks were removed from 459 and 480 Pleasant Street. No contaminated soil has been removed from the former dispenser area at 459 Pleasant Street. 5.3 Extent of Groundwater Contamination The extent of the dissolved gasoline contamination in the groundwater is shown on Figures Three and Four as the 10,000 and the 2,000 iso-contours. Again, our estimated extent is similar to what has previously been reported. 6.0 RISK CHARACTERIZATION On December 8, 1998, a Method Three Risk Characterization report for the site was prepared by O’Reilly, Talbot & Okun Associates, Inc of Springfield for ECS. It was prepared from the site information and sampling results provided by ECS. Free-phase gasoline was no longer present at the site. No public or private wells were known to be within 500 feet of the site. The contaminated soil was classified as S-3 and it was assumed that an Activity and Use Limitation (AUL) would be applied. The groundwater was incorrectly classified as GW-2 because there were occupied buildings within 30 feet of the site. The DEP has since determined that occupied buildings are defined as buildings occupied 24 hours per day. There are no occupied buildings within 30 feet of the site and therefore the groundwater should be classified as GW-3. The report concluded that conditions at the site did not present a significant risk to public welfare, environmental and public safety. It was unclear whether an AUL was required and its extent. Page 23 PENNEY ENGINEERING, INC Based upon the reoccurrence of the free-phase gasoline, we have prepared a brief Method One Risk Characterization presented below. 6.1 Selection of Method Method One, as described in Section 40.0970 of the MCP, has been selected to characterize the risk of harm to health and public welfare posed by the current conditions at the site. Method One relies upon the use of specified numerical standards for selected chemicals in the groundwater and soil to characterize the risk of harm. These are published for each of the contaminants of concern identified at the site. 6.2 Nature and Extent of the Contamination and Contaminants of Concern The nature and extent of the contamination detected at the site is described fully in Section 5.0. The extent is shown on Figures Three and Four. 6.3 Identification of Potential Human and Environmental Receptors Based upon the current use of the property, the potential human receptors include the employees and customers of the many businesses along Pleasant Street. Typically, employees and customers of the businesses are present at the site for limited periods of time, less than eight hours per day. Potential future human receptors may include employees of businesses that may occupy the buildings which overlie the site in the future and construction crews involved in the future development or maintenance of the site. Environmental receptors on or near the site include the Mill River, which is located approximately 600 feet east of the site. 6.4 Identification and Site Activities and Uses The current uses at the site were previously presented in Section 2.2. The site is expected to be used by commercial businesses. Potential soil intrusive activities, such as excavation and construction conducted during future site development or installation and maintenance of utilities, are considered reasonably foreseeable future activities. The site is located within a non-productive aquifer. The site and surrounding areas are supplied with municipal water. Page 24 PENNEY ENGINEERING, INC 6.5 Identification of Exposure Points 6.5.1 Soil In accordance with Sections 40.0924 of the MCP, for a Method One risk characterization of soil, the exposure points shall be defined at the horizontal and vertical distribution of the contaminants in the soil in combination with the applicable soil categories. A majority of the site is paved or covered with buildings. The gasoline contamination is primarily located in the groundwater at depths of eight to 10 feet. Based upon the limited soil analysis that was conducted by ECS, we have assumed the soil exposure points to be from zero to 10 feet within the area of NAPL shown of Figures Three and Four. 6.5.2 Groundwater In accordance with Section 40.924 of the MCP, for a Method One risk characterization of the groundwater, the potential exposure points include the nearest top of a well screened within the horizontal and vertical distribution of the oil and/or hazardous materials in the groundwater. The iso-contours for the total BTEX compounds and the C5 – C8 VPH aliphatics fraction from our April 25, 2002 sampling results are plotted on Figures Three and Four, respectively. We have determined the groundwater exposure points to be the monitoring wells located within the 10,000 and 2,000 iso-contours. 6.6 Identification of Exposure Point Concentrations 6.6.1 Soil As stated in Section 3.1, in 1997 ECS advanced 25 additional borings, but only analyzed one soil sample from boring SB-4 located adjacent to the northeastern corner of the dispenser pad. Reportedly, it was the most contaminated soil they had encountered. Table Four summarizes the soil exposure point concentrations for the site based upon the results for SB- 4. Page 25 PENNEY ENGINEERING, INC TABLE FOUR Soil Exposure Point Concentrations Contaminant of Concern Exposure Point Exposure Point Concentration (mg/l) VOCs (mg/kg) MTBE SB-4 (12-13’) 58 Benzene SB-4 (12-13’) 43.5 Toluene SB-4 (12-13’) 363.5 Ethylbenzene SB-4 (12-13’) 116.5 Xylenes SB-4 (12-13’) 555.0 MTBE SB-4 (12-13’) 58 6.6.2 Groundwater Exposure point concentrations were determined from only our most recent April 25, 2002 groundwater results. The groundwater results collected prior to that time was excluded from the evaluation of exposure point concentrations. The highest contaminant concentrations in the groundwater would have been detected in the samples from monitoring wells MW-9 and MW-12, but they were not analyzed because of the free-phase gasoline. For each contaminant, the highest recent groundwater sampling result from Table Two was used as the exposure point concentration. Table Five summarizes the groundwater exposure point concentrations. Page 26 PENNEY ENGINEERING, INC TABLE FIVE Groundwater Exposure Point Concentrations Contaminant of Concern Exposure Point Exposure Point Concentration (mg/l) VPHs C5-C8 aliphatics MW-1 34,000 C9-C12 aliphatics MW-1 9,500 C9-C10 aromatics MW-1 18,000 Target VOCs MTBE MW-8 7 Benzene MW-1 12,000 Toluene MW-1 32,000 Ethylbenzene MW-1 4,700 Xylenes MW-1 23,500 Naphthalene MW-2A 400 6.7 Identification of Exposure Pathways Future intrusive soil activities may expose workers to the groundwater contamination by dermal absorption and/or ingestion, if excavation activities reach depths below the groundwater table. The depth to groundwater at the site is approximately eight to ten feet. There are currently no basements within 30 feet of where the contamination has been detected at the site. The contaminants detected in the groundwater are not expected to escape to the atmosphere by volatilization or by wind erosion, so the potential for human exposure by inhalation is extremely low. The groundwater at the site is not used for any purpose. Based upon the groundwater flow direction, the groundwater contamination detected at the site is not expected to result in detectable concentrations of the contaminants in the Mill River. Therefore, human exposure to the groundwater contamination by direct contact or ingestion of the groundwater or surface water is unlikely. 6.8 Identification of Soil and Groundwater Categories Based upon the receptor and exposure information assumed by Penney Engineering and the criteria listed in Section 40.0933 of the MCP, the soil at the site is classified as S-1 and S-2. The soil categories were determined based upon the following: Page 27 PENNEY ENGINEERING, INC · The frequency and intensity of children at the site is considered low; · The frequency of use of the site by adults may be considered high because of the employees, but the intensity of adult use is considered low because they are in buildings without basements; · A majority of the site is paved or occupied by a building or Pleasant Street; and · A majority of the soil contamination at the site is located at depths greater than three feet. The shallow contaminated soil known to be around the dispensers and which may be present in other areas of the site are classified as S-1. The remaining contaminated soil is classified as S-2 because it is at depths of eight to 10 feet and in areas covered with pavement or a building. Groundwater is classified as GW-2 if there is a potential for oil or hazardous waste vapors to migrate from the groundwater into an “occupied building or structure”. The DEP attempted to define an occupied building or structure in the February 1995 Special Edition #4 of Q&A and also as Question 143 in the March 25, 1993 Master Q&A. In summary, an occupied building or structure is a confined space were a person may be subjected to significant exposure to harmful vapors. A house were people may be present 24 hours per day is clearly an occupied building. An office building where workers are only present eight hours a day may or may not be considered an occupied building. A storage garage is not. Groundwater is classified as GW-1 if it is a source of drinking water. The regulations in 310 CMR 40.0900 provide general guidance on classifying groundwater. It is the opinion of Penney Engineering that the groundwater at the site is classified as GW-3 for the following reasons: 1. The site is located within a non-productive aquifer, there are reportedly no public or private wells within 500 feet of the site and municipal drinking water is available along Pleasant Street. 2. The depth to groundwater is eight to 10 feet and the soil from the ground surface to eight feet is of low permeability. 3. Only four commercial buildings are located above the contaminated groundwater. Workers are only in the buildings eight to 10 hours a day. None of the buildings have basements. No one has ever reported gasoline odors in any of the buildings over the past 20 years. In 1997, ECS failed to detect any significant vapors in the surrounding Page 28 PENNEY ENGINEERING, INC utilities or in the four buildings by screening with a HNu PI-101 PID, a Model 580B OVM and quantitative laboratory analysis. On April 25, 2002, we failed to detect any significant vapors while screening the indoor air in the four buildings with an OVM. All four buildings are used to service automobiles containing gasoline. 6.9 Applicable Method One Cleanup Standards The Method One S-1/GW-3 and S-2/GW-3 cleanup standards for soil and GW-3 cleanup standards for groundwater were selected from the tables in Sections 40.0974 and 40.0975 of the MCP. 6.10 Comparison of Exposure Point Concentrations to the Method One Cleanup Standards Table Six compares the soil exposure point concentrations to the Method One S-1/GW-3 and S-2/GW-3 cleanup standards. TABLE SIX Comparison of Soil Exposure Point Concentrations Cleanup Standards Exposure Point Contaminant (mg/kg) Conc S-1/GW-3 S-2/GW-3 SB-4 (12’13’) MTBE 58 100 200 SB-4 (12-13’) Toluene 363.5 400 2,500 SB-4 (12-13’) Ethylbenzene 116.5 500 500 SB-4 (12-13’) Xylenes 555.0 500 2,500 SB-4 (12-13’) Benzene 43.5 40 200 The exposure point concentrations in Table Six should only be compared to the S-2/GW-3 cleanup standards because the sample was collected from a depth of 12 to 13 feet. As shown in Table Six, none of the exposure point concentrations for the one soil sample analyzed from under the dispenser pad exceeded the S-2/GW-3 cleanup standards. Table Seven compares the groundwater exposure point concentrations to the Method One GW-3 cleanup standards. Page 29 PENNEY ENGINEERING, INC TABLE SEVEN Comparison of Groundwater Exposure Point Concentrations Cleanup Standards Exposure Point Contaminants Exposure Point Concentration (mg/l) GW-3 VPHs MW-1 C5-C8 aliphatics 34,000 4,000 MW-1 C9-C12 aliphatics 9,000 20,000 MW-1 C9-C10 aromatics 18,000 4,000 MW-8 MBTE 7 50,000 MW-1 Benzene 12,000 7,000 MW-1 Toluene 32,000 50,000 MW-1 Ethylbenzene 4,700 4,000 MW-1 Xylenes 23,500 50,000 MW-2A Naphthalene 400 6,000 As shown in bold in Table Seven, the C5-C8 aliphatic VPH fraction, benzene, and ethylbenzene exceeded the GW-3 cleanup standards. 6.11 Conclusions of Method One Risk Characterization As shown in Table Six, the soil exposure concentrations for the one soil sample from SB-4 did not exceed any of the S-2/GW-3 cleanup standards. That may indicate that the deep, contaminated soil at the site may not present a risk. Additional sampling is required to determine the risk from shallow, contaminated soil and if an AUL will be required to maintain the S-2/GW-3 soil category. As shown in Table Seven, the groundwater exposure point concentrations for the site are above the applicable Method One GW-3 cleanup standards. Therefore, the groundwater contamination at the site may present a risk of harm to human health, public welfare or the environment. 6.12 Characterization of Risk to Safety Based on the analysis results and the exposure information, the contamination detected at the site does not pose a significant risk to safety. The gasoline contamination detected at the site does not pose a threat of fire or explosion nor does it exhibit the characteristics of Page 30 PENNEY ENGINEERING, INC corrosivity, reactivity or flammability, and the potential for the gasoline to enter the utilities or the building are considered low based upon the extensive air sampling program conducted by ECS in 1997. 7.0 SUMMARY OF SITE CONDITIONS THAT WARRANT REMEDIAL ACTIONS A Method One risk characterization determined that the groundwater exposure point concentrations at the site are above the applicable Method One GW-3 cleanup standards. Therefore, remedial actions are warranted at the site to reduce the risk of harm to human health, public welfare or the environment. Additional sampling and investigations are required to determine if the soil contamination presents a risk. 8.0 REMEDIAL ACTION PLAN As discussed in Section 7.0, a Method One risk characterization has determined that the gasoline contaminated groundwater at the site presents a significant risk and requires that comprehensive remedial actions be implemented at the site. As a result, an evaluation of the applicable remedial technologies was conducted. The most applicable technologies were screened to determine the most applicable remedial technologies which were then combined as remedial action alternatives. A detailed evaluation of the alternatives was then conducted to determine the most applicable remedial action alternative. This section of the Phase III/IV Plan presents the results of our Phase III Identification, Evaluation and Selection of Comprehensive Remedial Action Alternatives. 8.1 Identification and Evaluation of the Remedial Technologies In order to effectively identify and evaluate the applicable remedial technologies, the following assumptions were made: 1. The gasoline contamination in the groundwater at the site exceeds the Method One, GW-3 cleanup standards and must be remediated within three to five years. The free- phase gasoline and the gasoline contamination in the soil must initially be removed in order to expedite the remediation of the groundwater. 2. A heated and secure area for the treatment equipment is not available at the site. The equipment shall be housed in a treatment trailer to be located adjacent to the office building. Page 31 PENNEY ENGINEERING, INC 3. The amount of iron and manganese in the groundwater is assumed to be relatively high and shall cause fouling of air stripping equipment. 4. Permanent electrical service of 230 VAC, 100A, single-phase is available on the outside of the office building to operate the treatment equipment. 5. Explosion-proof equipment shall not be required. All wiring within the treatment trailer shall be installed a minimum of 18 inches above the floor of the treatment trailer. 6. The treated groundwater shall be recharged into the groundwater upgradient of the release area which is thought to be the former dispensers along Pleasant Street. 7. Recovery wells and SVE zones shall be installed on both sides of Pleasant Street to expedite the remediation of the site. The owner of 480 and 492 Pleasant Street has issued written authorization to install a recovery well on his property. 8. The existing soil conditions require the installation of large diameter recovery wells with French drains to allow flow rates up to 10 gpm from each well. 9. Any recovered gasoline shall be manually bailed from the recovery wells. This shall save approximately $20,000 for automatic skimmers. 10. All the piping shall be installed underground to prevent freezing and not restrict use of the properties. 11. Dewatering shall not be conducted during the installation, but provisions shall be made to quickly conduct dewatering if required. 12. Access must not be restricted to the northern curb cut at 480 Pleasant Street. 13. The concrete slab for the treatment trailer shall be removed once the site is remediated because it is not adequately setback from the property line. 14. Any significantly contaminated soil encountered during the installation of the treatment system shall be used as backfill in the SVE zones or recycled off-site under a Bill of Lading. Page 32 PENNEY ENGINEERING, INC 8.2 Initial Screening of the Most Applicable Remedial Action Alternatives A wide range of technologies to remediate the gasoline in the soil and the groundwater at the site were evaluated based upon the assumption that the individuals and expertise needed to effectively implement the available technologies are available. The technologies selected during the initial screening were subsequently assembled into combinations of remedial action alternatives. The following technologies were determined to be applicable to achieve a level of no significant risk at the site as defined by 310 CMR 40.0900: Aqueous Phase Carbon Adsorption The contaminated groundwater would be pumped through large canisters of aqueous phase carbon where the dissolved gasoline contaminants would be adsorbed onto the carbon. The treated groundwater could be recharged back into the groundwater. Particle filters would be required and need periodic replacement. Dissolved iron would precipitate out in the carbon canisters causing premature clogging. Spent carbon canisters must be disposed of off-site as a hazardous waste. Aqueous phase carbon cannot be regenerated on-site. The carbon canisters must be housed and heated to prevent freezing. This technology was considered applicable. Air Stripping Air stripping is a mass transfer process where the dissolved gasoline contaminants would be transferred from the groundwater into an airstream. Ambient air is usually forced up through a packed tower as the groundwater is sprayed into the top of the tower. Low-profile, cascading units are also available. Heating of the air improves the transfer. As with carbon adsorption, dissolved iron produces fouling of the packing and freezing is a problem during winter months. Similarly, the treated water must be recharged back into the groundwater. This technology was considered applicable. Biodiffused Aeration Biodiffused aeration is a mass transfer process similar to air stripping where the dissolved gasoline contaminants would be transferred from the groundwater into an airstream. Bacteria and nutrients are also injected into an aeration tank to allow biodegradation of the contaminants in the tank and in the recharge area of the aquifer. A vacuum is applied above water in the aeration tank with multiple stripping stages. Ambient air is drawn into the bottom Page 33 PENNEY ENGINEERING, INC of the water through diffusers. The diffusers allow for uniform distribution of the air bubbles throughout the water column. Diffused aeration is not as efficient as air stripping, but it simultaneously allows for iron and manganese removal, therefore fouling is greatly reduced. As with air stripping, heating the air improves the transfer. Similarly, freezing is a problem during the winter months and the treated water must be discharged in an appropriate manner. This technology was considered applicable. Bioremediation In-vessel or in-situ bioremediation promotes the biological metabolism of the dissolved gasoline compounds. Nutrients are usually required. For in-vessel bioremediation, groundwater would be pumped into a large bioreactor tank from a recovery well. For in-site bioremediation, bacteria, nutrients and oxygen are injected into the contaminated groundwater. As the concentrations of the dissolved gasoline contaminants decrease, so too does the metabolic rate. Based upon this limitation and the relatively small amount of contamination, this technology was only considered of combined with another technology. Soil Vapor Extraction Soil vapor extraction (SVE) is a very economical method of removing volatile organic compounds from soil located above the groundwater table. A series of vertical or horizontal recovery wells are normally installed in dry, contaminated soil. The soil gas is then withdrawn from the contaminated soil with a blower or compressor and treated through vapor phase carbon or an incinerator before being discharged to the air. Based upon the brief success of the SVE system installed by Acadian, this technology was considered. Air Sparging With this technology air is bubbled into the uppermost portion of an aquifer. The air bubbles induce a transfer of the dissolved gasoline contaminants as they travel up through the groundwater and vadose zone of the saturated soil. The air would then be drawn into the suction side of a blower through a buried collection network of perforated piping as with an SVE system. The air would be passed through vapor phase carbon or an incinerator before being discharged to the atmosphere. Ambient air containing oxygen can be fed into the airstream along with nutrients to promote biological activity. No heating of the system is required and there is no water discharge. Due to the low permeability of the soil and the restricted access created by Pleasant Street, this technology was not considered. Page 34 PENNEY ENGINEERING, INC Vapor Phase Carbon Vapor phase carbon is used for air emissions control by passing an airstream containing gasoline contaminants from an air stripper, a biodiffuser or an SVE system process through a large vessel of vapor phase carbon where the gasoline compounds would be adsorbed onto the carbon. The treated air would then be discharged to the atmosphere. Disposable canisters of carbon could be used or a specially designed carbon vessel could be periodically regenerated before a breakthrough of contaminants occurs. The regeneration procedure utilizes steam to strip the contaminants from the carbon. The contaminated steam is then condensed into contaminated condensate water and free-phase product which must be properly disposed of or treated. The contaminated condensate could be treated through a groundwater treatment system. This technology was considered. Bioslurping Bioslurping attempts to skim free-phase petroleum products off the top of the groundwater by vacuum. A large volume of air, water and petroleum are withdrawn from the groundwater table through a skimmer pipe, a phase separator and a blower. The air is drawn through the vadose zone of the soil as in soil venting. The elevation of the skimmer pipe must be periodically adjusted to remain just above the fluctuating groundwater table. Because access to the free-phase gasoline is restricted by Pleasant Street, this technology was not considered. Catalytic Incineration Catalytic incineration is used for air emissions control by passing an airstream containing the gasoline contaminants from either an air stripper, a biodiffuser or an SVE system through a catalytic incinerator where temperatures are held above 600°C. Inside the catalytic incinerator more than 99% of all combustibles are oxidized to CO2 and H2O. It cannot be used with non-combustible contaminants such as chlorinated solvents. The treated air would then be discharged to the atmosphere. This process is often used when the contaminant concentrations are very high, when the contaminants do not adsorb onto carbon very well, or if the disposal of the recovered contaminants from vapor phase carbon is very expensive or impractical. As the concentrations of the contaminants decrease, propane, electricity or natural gas must be supplied to maintain the temperature in the incinerator which can be Page 35 PENNEY ENGINEERING, INC expensive. This technology was not considered due to the relatively high capital costs and the low concentrations expected. Soil Removal The removal and recycling or disposal of contaminated soil can be an effective method for remediating soil contamination. The removal of contaminated soil also aids in the remediation of groundwater by achieving a reduction in the contaminant mass with the potential to leach into the groundwater. Soil removal is often limited by the presence of contaminated soils beneath buildings or at great depth. In cases where the contaminated area is extensive, soil remove becomes less cost effective. This technology was not considered applicable for the remediation of soil contamination at the site because it extends under Pleasant Street and buildings. Activity and Use Limitation As an alternative to active remediation of soil, an Activity and Use Limitation (AUL) could be applied to contaminated soil areas. Engineering controls (e.g. concrete and/or paving) would be used to prevent exposure to the contaminated soil. A survey, a recordable plan and recording at the Registry of Deeds is required. Given the nature of the contaminants in soil at the site and the tendency for some of these contaminants to leach from soil into groundwater, this remedial alternative was only considered if combined with another alternative. Monitored Natural Attenuation and Enhanced Natural Attenuation Monitored natural attenuation is a remedial alternative where the natural processes of dispersion and biodegradation are monitored over time to observe the reduction of contaminants in groundwater. In most cases, the removal of the vast majority of contaminated soil must occur prior to observing satisfactory groundwater contaminant reduction trends. The natural processes can be enhanced by the introduction of remedial additives, such as oxygen releasing compounds or bacteria. The time necessary for remediating a site using natural attenuation is typically longer than when an active remedial alternative is used. Given that the gasoline at the site has not been remediated by this technology for the past 20 years it was not considered. It may be employed once a majority of the gasoline contamination is removed by active means. Page 36 PENNEY ENGINEERING, INC 8.3 Detailed Evaluation of the Remedial Action Alternatives After screening the applicable technologies, the following alternatives were selected to provide for the quickest, most cost-effective cleanup of the gasoline in the soil and the groundwater at the site. The associated risks with implementing any of the remedial alternatives would be minimal during the excavation of required trenching, installation and operation of the treatment system. The criteria used to evaluate the Remedial Action Alternatives included: 1. Are the technologies used in the alternative proven? 2. Is the contamination destroyed, transformed to be less toxic, reused, or recycled? 3. Can the alternative be safely constructed and operated? 4. Shall the operation of the alternative reduce the risk at the site in a timely manner? 5. Is the alternative economical to construct and operate? 6. Shall the operation of the alternative produce waste? 7. Does the alternative require approvals, permits or licenses? 8. Can the alternative be economically removed and salvaged? The alternatives included: 1. A groundwater treatment system utilizing disposable aqueous phase carbon and a soil vapor extraction system initially utilizing a catalytic incinerator then disposable vapor phase carbon for air emissions control. 2. A groundwater treatment system utilizing a biodiffuser and a soil vapor extraction system both utilizing steam regenerative vapor phase carbon for air emissions control. A brief evaluation of the two remedial action alternatives is as follows: Alternative #1 - Disposable Carbon Adsorption Treatment System Groundwater would be pumped at approximately 200 gallons per minute from two recovery wells and then passed through two, 2,000-pound canisters of aqueous phase carbon. The canisters would be installed in a large trailer or container to prevent freezing. The treated Page 37 PENNEY ENGINEERING, INC water would be discharged into a recharge well located upgradient of the release area. Free- phase gasoline could be manually bailed from the recovery wells. All the piping would be installed underground. The carbon would be periodically replaced as it becomes saturated. The SVE system would be installed as three zones. The blower and two, 1,000-pound canisters of vapor phase carbon would be installed on a separate trailer or container. Freezing would not be a problem. The technologies are proven. They have been successfully used at numerous sites. The gasoline contaminants in the groundwater would be readily adsorbed onto the carbon and ultimately destroyed during the incineration or reactivation of the spent carbon. The gasoline vapors from the SVE system would also be readily adsorbed onto the carbon and destroyed. The system would reduce the risk from the contamination in two to five years. The operation of the system would be very expensive because of the required analysis to monitor breakthrough of the carbon and the costs to frequently recharge the carbon. Spent carbon would be produced as a waste. Only a building and electrical permit would be required to install the system. Hazardous waste manifest would be required to transport the spent carbon off-site. The system could be very easily removed. The piping would be cut and capped to safely remain underground. There would be very little salvage value. An estimate of the costs is as follows: Task Estimated Cost 1. Review reports, conduct limited assessment activities and prepare a Phase III/IV Plan for submission to the DEP $ 12,000 2. Prepare construction plans then specify, order, purchase and receive equipment 10,000 3. Apply for a building permit 850 4. Select contractors and coordinate the installation 3,500 5. Install recovery wells, install SVE zones, connect to existing piping under Pleasant Street, pour pad for trailers, and install recharge well 32,000 6. Purchase treatment equipment and install carbon canisters, trailers, used incinerator and the required valves, gauges, filters 55,000 7. Operate the system at 20 gpm for five years; inspect weekly to change filters and bail gasoline; sample well quarterly; and prepare reports for the DEP Analysis: 30,000 Labor: 46,000 Page 38 PENNEY ENGINEERING, INC 8. Recharge one aqueous, and phase one vapor phase carbon canister every two months for five years, with off-site disposal of carbon and gasoline Materials: 60,000 Labor: 53,500 Disposal: 20,000 9. Sample soil 8,000 10. Remove system Labor: 3,000 Subtotal: 333,850 11. Salvage value (500) 12. Prepare RAO Statement without an AUL 8,500 13. Contingency at 20% 68,370 Total Estimated Cost: $ 410,220 Alternative #2 - Biodiffused Aeration with Regenerative Vapor Phase Carbon Groundwater would be pumped from the two recovery wells and then passed through a biodiffuser located in a trailer, as shown on the Remedial Action Site Plan. The treated groundwater would then be discharged into the recovery well. Bacteria may also be added to the biodiffuser to inoculate the contaminated groundwater to promote the biological breakdown of the gasoline contamination in the biodiffuser and in the recharge area. The airstream from the biodiffuser would be piped to a regenerative vapor phase carbon vessel located on a pad adjacent to the trailer. Task Estimated Cost 1. Review reports, conduct limited assessment activities and prepare a Phase III/IV Plan for submission to the DEP $ 10,000 2. Prepare construction plans then specify, order, purchase and receive equipment 15,000 3. Apply for a building permit 850 4. Select contractors and coordinate the installation 3,500 Page 39 PENNEY ENGINEERING, INC 5. Install recovery wells, install SVE zones, connect to existing piping under Pleasant Street, pour pad for trailer, and install recharge well 32,000 6. Purchase treatment equipment and fabricate trailer 50,000 7. Operate the system at 20 gpm for three years; inspect weekly to change filters and bail gasoline; sample quarterly; and prepare reports for the DEP Analysis: 15,000 Labor: 36,000 8. Regen carbon vessel monthly for the first year then every other month. 48,000 9. Sample Soil 8,000 10. Remove System Labor: 3,000 Subtotal: 221,350 11. Salvage value (15,000) 12. Prepare RAO Statement without an AUL 8,500 13. Contingency at 10% 21,485 Total Estimated Cost: $ 236,335 The associated costs represent estimated values based upon our experience on similar sites. We have estimated the cleanup to take three to five years depending upon the selected alternative. 8.4 Selected Remedial Action Alternative We have evaluated the applicable remedial technologies and determined that the most appropriate alternative would include pumping the contaminated groundwater from two recovery wells in order to first depress the groundwater table to allow a majority of the free- phase gasoline to be removed by manually skimming any recovered gasoline from inside the large diameter recovery wells. Based upon the available assessment information, the center of the free-phase gasoline and the dissolved plume appears to be located directly under Pleasant Street as shown on Figures Three and Four. A second recovery well to be located at 480 Pleasant Street is being proposed to expedite the remediation, as shown on the Remedial Action Site Plan. We are initially hoping to utilize the former product piping under Pleasant Street to pipe to the optional recovery well. If we cannot locate the piping or if it is Page 40 PENNEY ENGINEERING, INC not suitable, we shall install the second recovery well at 480 Pleasant Street and then request approval from the Massachusetts Highway Department to trench across Pleasant Street at a later date. The SVE system shall be installed as three zones, as shown. The treatment equipment shall be housed in an enclosed trailer to be located adjacent to the office building at Pleasant Journey on a concrete pad, enclosed by chainlink fence. The remainder of the treatment system shall be installed underground to prevent freezing and damage. The groundwater being pumped shall be treated through a biodiffuser with regenerative vapor phase carbon for air emission controls. The treated groundwater shall be recharged back into the ground, upgradient of the contamination, to promote flushing and biological remediation. Once a majority of the available free-phase gasoline is removed, the SVE shall be activated to remove the bound free-phase gasoline from the pore spaces of the dewatered saturation zone above the depressed groundwater table. Once the SVE system has removed the bound free-phase gasoline, the groundwater shall continue to be pumped, treated and discharged upgradient of the contamination until the dissolved gasoline contaminants are consistently reduced below the Method One GW-3 cleanup standards for four consecutive sampling quarters. Remedial additives may be periodically injected into the recharged groundwater. 8.5 Feasibility of Implementing the Selected Remedial Action Alternative The installation of the selected biodiffused aeration and soil vapor extraction treatment system is feasible. The associated technology is proven and relatively simple to install. The treatment technology utilizes air stripping and bioremediation of the gasoline contaminants in the groundwater. Any recovered gasoline would be manually bailed from the recovery wells. The three SVE zones shall allow the remaining 10% of the free-phase gasoline to be removed from the soil. Both are proven technologies. The proposed pumping and recharge scheme shall circulate clean, oxygen rich water with bacteria and nutrients through the limited area of contamination. The pumping rate can be increased in order to decrease the treatment period. The contaminant concentrations shall be reduced to approach background. The installation of the selected biodiffused aeration treatment system shall result in a permanent solution to the risk at the site. The system is also relatively inexpensive to install and operate. The expenditure of funds to install and operate the selected remedial action alternative is justified. Page 41 PENNEY ENGINEERING, INC 9.0 REMEDY IMPLEMENTATION PLAN 9.1 Relevant Contacts Pleasant Journey Used Cars, Inc has assumed the responsibility for implementing selected remedial action alternative at the site in accordance with MGL c. 21E and the Massachusetts Contingency Plan. The name, address and telephone number of the contact person is: Mr. Robert P. Kalish, President PLEASANT JOURNEY USED CARS, INC 459 Pleasant Street Northampton, MA 01060 (413) 774-6559 The name, address and telephone number of the Licensed Site Professional is: Mr. Ralph P. Penney, President PENNEY ENGINEERING, INC 125 High Street Mansfield, MA 02048 (508) 261-1288 LSP #7755 A complete list of all our contacts is included on our Contact List included in Appendix D. 9.2 Design of the Selected Remedial Action Alternative The design of the proposed treatment system is shown on the Remedial Action Site Plan and the Installation Plan included in the rear pocket. The system shall be installed as shown. We propose to first remove the free-phase gasoline by depressing the groundwater in the two recovery wells. Any accumulated gasoline shall be manually skimmed from the recovery wells and stored in two collection drums. Once the free-phase gasoline is removed, we shall activate the SVE system installed as three zones. The SVE system shall remove the remaining 10% of the free-phase gasoline that normally remains in the pore spaces of the soil as globules. Pleasant Street limits the extent of the SVE system. The pumped groundwater shall be treated through the biodiffuser and the clean, oxygen-rich water shall be recharged into a recharge well located south of the former tanks and dispensers. The recharged water shall promote biological remediation of the gasoline contamination in the surrounding soil and groundwater. It shall also drive the free-phase gasoline and dissolved Page 42 PENNEY ENGINEERING, INC gasoline contaminants toward the two recovery wells. The biodiffuser is expected to continue operating one to three years after the free-phase gasoline has been removed and the SVE system have done their work. The biodiffuser, SVE blower, moisture separator, and the electronics shall be housed in a heated trailer to be setup adjacent to the office building as shown. A regenerative vessel of vapor phase carbon shall be setup adjacent to the trailer along with the two gasoline collection drums and three drums used to steam clean (regenerate) the carbon. We shall construct a concrete pad to support the trailer, the carbon vessel and the drums. We shall also secure the area with a six-foot high, green vinyl coated, chain link fence. Approximately once a month we shall have to park our regen trailer on Fulton Avenue to steam clean the carbon vessel. The recovered groundwater shall be discharged into the biodiffuser at two to 20 gpm. The ideal flow rate shall be determined by measuring the drawdown in the monitoring wells near the recovery wells. The groundwater shall flow through a series of bafflers and weirs in the tank. Ambient air, from outside the trailer, at approximately 100 cfm, shall be drawn through the water causing the volatile gasoline contaminants to be “stripped” from the water. The discharge pump shall be wired to only operate if the blower is running. There may be a manual override. The contaminated air shall be drawn into a 2.0 HP regenerative blower, which shall slightly raise the air temperature to reduce the relative humidity and discharge it through the SVE blower into a vessel of vapor phase carbon located outside the trailer. The SVE blower shall operate at 250 cfm with 100 cfm coming from the biodiffuser. The 150 cfm airflow shall remove soil gas from the three SVE zones and discharge the air into the carbon vessel. The Model 10-M3-E7 carbon vessel shall be 3.0 feet in diameter with a seven-foot bed of approximately 1,330 lbs of 4x10 mesh, coconut-based, vapor phase carbon. The carbon shall readily adsorb the volatile gasoline contaminants. The carbon vessel shall contain sample ports at 12” intervals in order to monitor breakthrough or saturation of the carbon. The clean air shall be discharged to the atmosphere at a height of at least 12 feet. Valving shall be installed to allow the carbon vessel to be by-passed once the concentrations decrease. The treated groundwater shall collect in a clear well within the biodiffuser tank. Level controls shall activate a 1.0 HP discharged pump. The treated groundwater shall be periodically pumped through a filter and discharged into the recharge well located upgradient of the contamination. The treated water shall be reinjected into the groundwater to flush the gasoline contaminants toward the recovery well. The discharged water shall be saturated with oxygen which shall promote biological remediation of the gasoline contaminants in the Page 43 PENNEY ENGINEERING, INC groundwater. Specific bacteria may be added to the first stage of the biodiffuser to promote bioremediation in the tank and in the groundwater. An off-gas opinion shall be prepared to determine the limits of the air discharge. The carbon vessel shall be periodically monitored with an organic vapor meter. Once the carbon has become saturated, the system shall be shutdown and the carbon shall be regenerated with steam from a mobile source by Penney Engineering. Any recovered gasoline shall be appropriately stored in one of the gasoline drums and properly disposed of by a licensed hazardous waste transporter. A permit to store the recovered gasoline from the Northampton Fire Department shall be posted at the site. The contaminated condensate from the regeneration process shall be allowed to cool and treated through the biodiffuser. The objective of the Phase IV Remedy Implementation Plan is to remediate the gasoline- contaminated soil and groundwater at the site. The proposed treatment system shall be operated until the concentrations of the dissolved, gasoline-related contaminants in the groundwater at the site are consistently reduced to below their respective Method One GW-3 cleanup standards for a period of 12 months. The system shall also operate until the residual soil contamination is reduced below the S-1/GW-3 cleanup standards. The system may be shutdown and the groundwater simply monitored once the concentrations are below the cleanup standards. 9.3 Required Permits and Licenses The following permits are anticipated to be required to install and operate the selected remedial action alternative: 1. Hazardous waste manifests shall be required to transport any recovered gasoline from the carbon regeneration process. 2. A Bill of Lading or manifest may be required to transport any contaminated soil encountered during the installation of the recovery well and underground piping for recycling or disposal. 3. An electrical permit from the Northampton Building Department. 4. A permit from the Northampton Fire Department to store less than 65 gallons of recovered gasoline. Page 44 PENNEY ENGINEERING, INC 5. A building permit from the Northampton Building Department. A copy of the April 25, 2003 Building Permit is included in Appendix D. An LSP Opinion shall be prepared to determine the discharge limits for the air, in accordance with 310 CMR 40.0049 and the DEP’s Off-Gas Treatment Policy, as amended. The opinion shall be submitted to the DEP with the first monitoring report. The opinion shall be submitted to the DEP prior to by-passing the vapor phase carbon and directly discharging to the atmosphere. 9.4 Health and Safety Procedures Health and safety procedures designed to protect health, safety, public welfare and the environment shall be implemented during the performance of all the proposed response actions. The procedures to be implemented shall be described in a separate Health and Safety Plan which shall comply with 310 CMR 40.0018. 9.5 Additional Notification Requirements Pleasant Journey Used Cars, Inc shall be responsible for notifying the DEP of any new information which becomes available while conducting the response actions which shall require a modification of this Phase III/IV Remedial Action and Remedy Implementation Plan. Any evidence of additional releases or threats of release shall be immediately reported to the DEP in accordance with the notification requirements of the MCP. 9.6 Imminent Hazard Evaluation Based upon our current understanding of the available information for the site, the limited area of free-phase and dissolved gasoline contaminated groundwater does not present an imminent hazard or a threat of a substantial release migration. After the treatment system has been installed, we shall conduct an investigation of the utilities. The presence of an imminent hazard and a substantial release migration shall be continuously evaluated during the implementation of the remedial response measures, in accordance with 310 CMR 40.0321 and 40.0006. 9.7 Implementation Schedule The treatment trailer has been fabricated and shall be tested next week. The pre-cast concrete structures have been designed, ordered and were delivered to the site on May 1 Page 45 PENNEY ENGINEERING, INC and 2, 2003. We are currently monitoring the elevation of the groundwater on a weekly basis and have tentatively scheduled the installation for the week of June 2, 2003. The two recovery wells, the recharge well, the three SVE zones, the concrete pad with the fence posts and all the underground piping shall be installed that week. The vapor phase carbon shall also be accepted for delivery. The carbon vessel and the treatment trailer shall be situated on the cured concrete pad. During the following week, the recovery pumps, the trailer and the dialer shall be wired. The air discharge from the biodiffuser and the SVE blower shall be piped to the carbon vessel. The trailer shall be leveled and set on blocks. The fence shall be installed and the system shall be started. 9.8 Operation and Maintenance The proposed treatment system shall be operated and maintained by Penney Engineering with help from the mechanics at Pleasant Journey. Initially, the system shall be inspected daily until the inlet concentrations stabilize and the breakthrough period for the vapor phase carbon is established. The system shall then be inspected weekly or more often it needed in accordance with 310 CMR 40.0191. The mechanics shall be trained to safely bail any recovered gasoline from the recovery wells on a weekly basis. All piping shall be installed underground. The site is currently occupied during the day by the employees of Pleasant Journey. A notice shall be installed on the exterior wall of the fenced area to alert residents to contact Pleasant Journey or Penney Engineering if there are any problems. The biodiffuser is supplied with a high-level shutoff switch wired to an alarm and an exterior strobe light on the trailer and a dialer to call Mr. Kalish and Penney Engineering. The moisture separator for the SVE system is wired similarly. It may be wired to an alarm in the station. The Northampton Fire and Police Departments shall be provided with telephone numbers to be called for routine questions and in emergencies. 9.9 Monitoring Program In accordance with 310 CMR 40.0047(3), Penney Engineering or someone from Pleasant Journey shall inspect the treatment system on a weekly basis. A monitoring log shall be completed during each inspection. Groundwater samples shall be periodically submitted to a Massachusetts-qualified laboratory and analyzed for VPHs. The biodiffuser is expected to remove up to 95% of the gasoline contaminants. The biodiffuser has not been designed to remove 100% of the contaminants because the treated water shall be recharged into the groundwater, upgradient of the contamination to be recaptured by one of the recovery wells. Page 46 PENNEY ENGINEERING, INC The existing monitoring wells MW-1, MW-2A, MW-9, MW-12 and ECS-5 shall be sampled immediately before the system is started. Specific monitoring wells shall be sampled on a quarterly basis. The groundwater samples shall be analyzed for concentrations of volatile petroleum hydrocarbons (VPHs) by the DEP method. The samples shall also be monitored for heterotrophic bacteria, pH, temperature, dissolved oxygen, nitrites and nitrates if bacteria is applied. Initially, the air from the SVE system and the biodiffuser shall be periodically screened with an organic vapor meter for the first two weeks until the carbon breakthrough period is determined. One air sample may be analyzed by a Massachusetts-certified laboratory for identification of the specific contaminants. After the first week of operation, the system shall be inspected and air samples shall be screened weekly or as warranted. In 1997, ECS conducted an extensive indoor air sampling program in the utilities and the four buildings. No significant vapors were detected. On April 25, 2002, we failed to detect any significant vapors while screening the four buildings with an OVM. Based upon the results of these two air sampling events, no additional air sampling shall be conducted. After the free-phase gasoline has been removed the residual gasoline down to 1.0 or 2.0 ppm in the soil gas, we shall collect representative soil samples from the former area of the free-phase gasoline. Up to 10 soil samples shall be collected from above and below the groundwater table. The samples shall be analyzed for VPHs. The results of the groundwater analyses, air sampling and monitoring logs shall be included in periodic monitoring reports sent to the DEP after the first 120 days, then every six months, in accordance with 310 CMR 40.0892, until the groundwater remains below GW-3 cleanup standards for a 12-month period. The monitoring reports shall describe the dates of the inspections. They shall describe any significant modification made to the treatment system since the prior report. They shall describe any problems and what measures were implemented to resolve the problems. The reports shall bear the name, license number, signature and seal of Ralph P. Penney as the LSP-of-Record for the site. Any unusual results shall be immediately orally reported to the DEP. Page 47 PENNEY ENGINEERING, INC 10.0 PUBLIC INVOLVEMENT ACTIVITIES In accordance with the public involvement requirements of the MCP, the Mayor of Northampton and the Health Agent shall be notified by Penney Engineering in writing of the implementation of this Phase III/IV Remedial Action and Remedy Implementation Plan. Notification shall be made by Penney Engineering concurrently with the submission of this document to the DEP. The notification shall include information about the purpose, nature and expected duration of the Phase IV activities. A copy of the notification letter sent to the Northampton officials is included in Appendix D. FIGURES PENNEY ENGINEERING, INC TABLE ONE Summary of Specific 1998 Groundwater Results Cleanup Standards Parameter MW-1 MW-4 MW-5 MW-6 MW-8 MW-9 MW-12 ECS-1 ECS-2 ECS-4 ECS-5 GW-2 GW-3 VPH (mmmmg/l) C5-C8 aliphatics < 200 1,300 330 3,400 350 6,300 1,600 1,500 < 200 < 200 1,400 1,000 4,000 C9-C12 aliphatics 30,000 19,000 2,800 15,000 1,700 33,000 27,000 3,500 < 200 1,000 2,400 1,000 20,000 C9-C10 aromatics 11,000 8,600 1,200 6,900 1,200 14,000 15,000 2,600 < 200 460 1,300 5,000 4,000 Target (mmmmg/l) MTBE 310 200 14 74 27 420 360 63 < 5 < 10 < 200 50,000 50,000 Benzene 10,100 4,800 170 720 77 8,700 7,500 630 < 5 11 1,700 2,000 7,000 Toluene 12,900 5,000 500 990 31 19,700 18,500 450 < 5 15 4,200 6,000 50,000 Ethylbenzene 3,800 1,400 290 860 27 3,400 4,500 170 < 5 11 2,600 30,000 4,000 Total Xylenes 17,300 8,100 970 2,160 109 18,600 22,700 855 < 5 56 12,300 6,000 50,000 Naphthalene 400 350 61 430 45 1,000 1,100 77 < 5 38 670 20 6,000 NS – No Standard PENNEY ENGINEERING, INC TABLE TWO Summary of Groundwater Results April 25, 2002 Cleanup Standards Parameter MW-1 MW-3 MW-5 MW-6 MW-7 MW-8 MW-2A ECS-1 ECS-5 BRIDAL-447 GW-2 GW-3 VPH (mg/l) C5-C8 aliphatics 34,000 <10 590 7,100 <10 1,000 15,000 2,400 12,000 16 1,000 4,000 C9-C12 aliphatics 9,500 <10 310 2,800 <10 120 4,300 760 3,400 30 1,000 20,000 C9-C10 aromatics 18,000 <10 510 11,000 <10 350 9,800 2,700 7,100 12 5,000 4,000 Target VOCs (mg/l) MTBE <500 <5 <5 <50 <5 7 <50 <5 <50 <5 50,000 50,000 Benzene 12,000 <5 22 460 <5 <5 1,500 320 4,700 <5 2,000 7,000 Toluene 32,000 <5 380 900 <5 <5 11,000 61 3,300 <5 6,000 50,000 Ethylbenzene 4,700 <5 150 670 <5 <5 2,200 180 1,600 <5 30,000 4,000 Xylenes 23,500 <10 680 3,230 <10 <10 9,300 714 5,100 <10 6,000 50,000 Naphthalene <500 <5 24 200 <5 <5 400 79 300 42 20 6,000 Total BTEX 72,200 <25 1,232 5,260 <25 <25 24,000 1,275 14,700 <25 NS NS NS - No Standard APPENDIX A PHASE III REMEDIAL ACTION AND PHASE IV REMEDY IMPLEMENTATION PLAN TRANSMITTAL FORM (BWSC-108) AND COPY OF DECEMBER 9, 2002 ACCESS LETTER FROM QUICKBEAM REALTY TRUST APPENDIX B LABORATORY ANALYSIS REPORT FOR THE GROUNDWATER SAMPLES COLLECTED BY PENNEY ENGINEERING ON APRIL 25, 2002 APPENDIX C BORING LOGS, WELL DATA SHEETS AND GROUNDWATER ELEVATION LOG APPENDIX D COPIES OF THE PUBLIC NOTIFICATION LETTER, APRIL 25, 2003 BUILDING PERMIT, AND OUR CONTACT LIST