rdms docid 109084 - semspub.epa.gov · current human exposures under control environmental...

RDMS DocID 109084

DOCUMENTATION OF ENVIRONMENTAL INDICATOR DETERMINATION Interim final 2/5/99

RCRA Corrective Action Environmental Indicator (El) RCRIS code (CA725)

Current Human Exposures Under Control

Facility Name: Exelon New Boston LLC (formerly Sithe New Boston Generating Station) Facility Address: 776 Summer Street. South Boston, MA Facility EPA ID #: Former #: 000845420 Currents MAROOOO10702

1. Has all available relevant/significant information on known and reasonably suspected releases to soil, groundwater, surface water/sediments, and air, subject to RCRA Corrective Action (e.g., irom Solid Waste Management Units (SWMU), Regulated Units (RU), and Areas of Concem (AOC)), been considered in this El determination?

X If yes - check here and continue with #2 below.

If no -re-evaluate existing data, or

If data are not available skip to #6 and enter "IN" (more information needed) status code.

BACKGROUND

Definition of Environmental Indicators (for the RCRA Corrective Action)

Environmental Indicators (EI) are measures being used by the RCRA Corrective Action program to go beyond programmatic activity measures (e.g., reports received and approved, etc.) to track changes in the quality ofthe environment. The two El developed to-date indicate the quality ofthe environment in relation to current human exposures to contamination and the migration ofeontaminated groundwater. An EI for non-human (ecological) receptors is intended to be developed in the fiiture.

Definition of "Current Human Exposures Under Control" EI

A positive "Current Human Exposures Under Control" EI determination ("YE" status code) indicates that there are no "unacceptable" human exposures to "contamination" (i.e., contaminants in concentrations in excess of appropriate risk-based levels) that can be reasonably expected under current land- and groundwater-use conditions (for all "contamination" subject to RCRA corrective action at or from the identified facility (i.e., site-wide)).

Relationship of EI to Final Remedies

While Final remedies remain the long-term objective ofthe RCRA Corrective Action program the EI are near-term objectives which are currently being used as Program measures ofthe Govemment Performance and Results Act of 1993, GPRA). The "Current Human Exposures Under Control" El are for reasonably expected human exposures under current land- and groundwater-use conditions ONLY, and do not consider potential fijture land- or groundwater-use conditions or ecological receptors. The RCRA Corrective Action program's overall mission to protect human health and the environment requires that Final remedies address these issues (i.e., potential fiiture human exposure scenarios, fijture land and groundwater uses, and ecological receptors).

Duration/Applicability of EI Determination

El Determination status codes should remain in RCRIS national database ONLY as long as they remain true (i.e., RCRIS status codes must be changed when the regulatory authorities become aware of contrary information).

RCRA RECORDS,CENTER FACILITY £y^gLo:n I.D. NO. oaf tR0000)0-70^ FILE i6c~__SEIS—-OTHER ' ^ AQl^O^H

Current Human Exposures Under Control Environmental Indicator (EI) RCRIS code (CA725)

Are groundwater, soil, surface water, sediments, or air media known or reasonably suspected to be "contaminated"' above appropriately protective risk-based "levels" (applicable promulgated standards, as well as other appropriate standards, guidelines, guidance, or criteria) from releases subject to RCRA Corrective Action (from SWMUs, RUs or AOCs)?

Groundwater Air (indoors)^ Surface Soil (e.g., <2 ft) Surface Water Sediment Subsurf Soil (e.g., >2ft) Air (outdoors)

Yes

X

No X X X X X

X

7

If no (for all media)-

Rationale/Kev Contaminants See following discussion See following discussion See following discussion See following discussion See following discussion See following discussion See following discussion

- skip to #6 and enter "YE" status c

X

appropriate "levels," and referencing sufficient supporting documentation demonstrating that these "levels" are not exceeded.

If yes (for any media) - continue after identifying key contaminants in each "contaminated" medium, citing appropriate "levels" (or provide an explanation for the determination that the medium could pose an unacceptable risk), and referencing supporting documentation.

If unknown (for any media) - skip to #6 and enter "IN" status code.

Rationale and Reference(s):

GENERAL

The Facility is an active electric power generating station. The geographic coordinates ofthe Facility are 42.339167 latitude and-71.035 longitude. The Facility is abutted to the north by the Boston Harbor Reserved Channel, to the west by Summer Street, to the south by East 1st Street, and to the east by an inlet ofthe Reserved Channel and a parcel belonging to the Massachusetts Bay Transportation Authority. A baseball field and a residential area are located to the south/southeast ofthe Facility, across East 1st Street. The Facility is situated on approximately 24.2 acres and includes a generation building that houses a working turbine, former electrical generating equipment, a guard shack, a former waste treatment building, a large gravel-covered area (former wastewater surface impoundments, three above-ground inactive bulk petroleum storage tanks, an outdoor electrical switchyard, and an office building. The Facility is surrounded by a chain-link fence topped with barbed wire, and access to the Facility is controlled by a security guard.

' "Contamination" and "contaminated" describes media containing contaminants (in any form, NAPL and/or dissolved, vapors, or solids, that are subject to RCRA) in concenfrations in excess of appropriately protective risk-based "levels" (for the media, that identify risks within the acceptable risk range).

^ Recent evidence (from the Colorado Dept. of Public Health and Environment, and others) suggest that unacceptable indoor air concentrations are more common in structures above groundwater with volatile contaminants that previously believed. This is a rapidly developing field and reviewers are encouraged to look to the latest guidance for the appropriate methods and scale of demonstration necessary to be reasonably certain that indoor air (in sfructures located above (and adjacent to) groundwater with volatile contaminants) does not present unacceptable risks.


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The property has been utilized for electricity generation since the 1890's. Prior to the 1890's, the property was utilized for non-related commercial activities, including ship repair. The original generating station was built in circa 1892 and operated by the Boston Edison Company (BECo). Historically, electricity was generated using steam turbines powered by coal and/or No. 6fuel oil boilers until the mid-1960 's, at which time only No. 6fuel oil was utilized to power two new horizontal turbine generators (Units 1 and 2) and a combustion je t turbine. In the mid-1980s the boilers were converted to run on natural gas, but with the capability to run on No. 6 fuel oil in emergency situations. In 1997, the Facility was purchased and operated by Sithe, LLC ("Sithe "). In 2003, the Facility was purchased by Exelon, which remains the current owner and operator. Units 1 and 2 were retired in 2002 and 2007, respectively. Currently, the combustion jet turbine is operated to generate electricity during high demand periods.

Institutional controls are in place and maintained to limit access to the property and for security purposes thereby limiting potential exposure to impacted soil. The property is surrounded with an intact chain-link fence and entry to the property is controlled. A security guard is stationed at the Site 24 hours per day. seven days per week, 365 days per year and the Site is protected with surveillance cameras that operate 24 hours per day, seven days per week, 365 days per year. Site workers and visitors are required to undergo Exelon Safety Training prior to accessing the Site. The potential for human exposure to impacted soil by trespassers and visitors is minimal

Assessment activities have been conducted over a period of several decades. Additional information is provided relative to four areas: 1) Fuel Oil Tank No. 3; 2) Former Wastewater Treatment Impoundments and Former Accumulation Areas; 3) the Southwest Courtyard Area; and, 4) Releases of Unknown Location. Assessment activities and results are provided below relative to Groundwater, Indoor Air, Surface Soil, Suiface Water, Subsurface Soil and Outdoor Air.

GROUNDWATER

Tank No. 3 : According to available records, historic releases of No. 6 Fuel Oil from Tank No. 3 at the Facility (see Site

Plan, attached hereto) have been reported and addressed under Massachusetts General Laws Chapter 21E (Chapter 21E) and accompanying regulations, 310 CMR 40.000 et seq. (the Massachusetts Contingency Plan or MCP) under the Release Tracking Number (RTN) 3-4519. While non-aqueous phase liquid (NAPL) was • initially detected in groundwater monitoring wells in the past, see GZA GeoEnvironmental. Inc. (GZA) Phase II — Comprehensive Site Assessment Report for Fuel Oil Tank No. 3, SITHE New Boston LLC dated August 9. 1999 and GZA Periodic Evaluation ofthe Temporary Solution Fuel Oil Tank No. 3. 776 Summer Street Boston, MA dated November 2004. quarterly gauging conducted since 2006 has not identified any NAPL in monitoring wells at the Facility, see_ OHI Ensjneerim. Inc. (OHI) Post Class C RAO Status Report. September 2010.

Groundwater analyses conducted by GZA did not identify dissolved petroleum constituents at concentrations at or above applicable groundwater standards under the MCP. See GZA Phase II -Comprehensive Site Assessment Report for Fuel Oil Tank No. 3. SITHE New Boston LLC dated Ausust 9, 1999 and GZA Periodic Evaluation ofthe Temporary Solution Fuel Oil Tank No. 3, 776 Summer Street. Boston, MA dated November 2004. Accordingly, a Class C RAO was filed with Mass. DEP in connection with RTN 3-4519 in August 1999. 5ee GZA Class C Response Action Outcome Report for Fuel Oil Tank No. 3. SITHE New Boston LLC dated Ausust 9. 1999. The Class C RAO indicates that a temporary solution has been achieved, ensuring the elimination of any substantial hazard and the identification, characterization and, to the extent feasible, elimination, control or mitigation of any source of OHM. The Class C RAO recommends no further action other than periodic monitoring. 5ee GZA Class C Response Action Outcome Report for Fuel Oil Tank No. 3. SITHE New Boston LLC.

The GZA Periodic Evaluation ofthe Temporary Solution Fuel Oil Tank No. 3. 776 Summer Street. Boston, MA dated November 2004 provides groundwater sampling analytical data collected in 2002 and 2004; the


Page 2.2

samples were collected from four monitoring wells (GZ-1, GZ-2, GZ-3, andGZ-7) and analyzed for Extractable Petroleum Hydrocarbons (EPH). The analytical results did not indicate the presence ofEPH in any ofthe samples. The Periodic Evaluation report also indicates that site conditions have not substantially changed since the initial RAO was submitted in 1999 and continues to recommend no further action other than periodic monitoring.

On December 11, 2007, Exelon New Boston, LLC, and its LSP, OHI Engineering, received a petition from ten (10) South Boston residents. The petition requested that Exelon New Boston, LLC's Tank No. 3 Release Site (RTN 3-4519) be designated as a Public Involvement Plan (PIP) Site under the MCP in accordance with 310 CMR 40.1404. On December 19, 2007, OHI submitted a reply to the petitioners confirming that the Tank No. 3 Release Site was eligible for, and was designated as, a PIP Site in accordance with the MCP. Interviews and meetings were held with the public during development of a Draft Public Involvement Plan. The Draft PIP was presented at a public meeting held at the South Boston Public Library and comments were received from the public. The Final PIP was prepared and submitted to the MassDEP on April 17, 2008. See FINAL PUBLIC INVOLVEMENT PLAN Tank No. 3 Release Site. DEP RTN 3-4519 dated April 17,2008 prepared by CLF Ventures and OHI Engineering. Since that time, semi-annual public meetings have been held at the Tynan Community Center in South Boston. The purpose ofthese meetings has been to update the public regarding the Tank No. 3 Release Site and the status ofthe Exelon New Boston Facility, in general.

Groundwater analytical data collected in December 2008 did not identify dissolved petroleum concentration at or above applicable MCP standards in groundwater monitoring wells downgradient of Tank No. 3. Concentrations ofCll-C22 Aromatics (petroleum hydrocarbons) were detected in one groundwater monitoring weU, MW-105, located upgradient of Tank No. 3. Concentrations ofthese Aromatics were 8,400 ug/L which exceeded the applicable (Method 1, GW-3) MCP groundwater standard of 5,000 ug/L. See OHI Ensineerins. Inc. Post Class-C RA O Status Report March 2009.

Recent groundwater analytical data from sampling events in A ugust 2009 and A ugust 2010 did not identify EPH. which includes the C11-C22 Aromatics, at or above the MCP Method 1 GW-3 standards in groundwater monitoring wells in the vicinit)' of Tank No. 3. This data has been submitted to DEP in the Post Class C RAO Status Reports dated September 2009 and September 2010. 5ee OHI Engineering, Inc. (OHI) Post Class C RAO Status Reports. September 2009 and September 2010

The OHI Ensineerins, Inc. Final Periodic Evaluation ofthe Temporary Solution dated November 2009 indicates that site conditions have not substantially changed since the initial RA O was submitted in 1999 and recommend no further action other than periodic groundwater gauging and annual groundwater sampling and analysis. A Draft Periodic Evaluation ofthe Temporary Solution was discussed at a Public Meeting in October 2009 and comments were received and addressed.

Groundwater is at a depth of approximately 9.5 to 10 feet below suiface grade and subsurface utilities are present at shallower depths above the water table surface. As indicated in the GZA Phase II Report, there are no known public or private drinking water wells at or within 500 feet ofthe Site. Based on Site activities and uses it is unlikely that an exposure pathway will result from groundwater contamination. See GZA Phase II — Comprehensive Site Assessment Report for Fuel Oil Tank No. 3, SITHE New Boston LLC.

The absence of NAPL and the presence of dissolved petroleum constituents below applicable MCP standards at downgradient locations indicate that groundwater in vicinity of Tank No. 3 is not known or reasonably suspected to be "contaminated" above appropriately protective risk-based "levels ".


Page 2.3

Former Wastewater Treatment Impoundments and Former Accumulation Areas: Mr. Jack Hughes, Exelon's Facility Manager, was interviewed regarding the former wastewater treatment

impoundments and former coal ash, metal hydroxide sludge, and fly and bottom ash accumulation areas. Mr. Hughes worked at the facility as an employee of Stone and Webster starting in 1999 and became an employee of Sithe/Exelon in 2000. He was permanently employed at the facility in 2004 as the Technical Manager. He was responsible for all remediation activities, engineering issues and project management. In 2007, Mr. Hughes was the Project Manager for decommissioning and retirement of Unit 1 and Unit 2 including the wastewater treatment system.

According to Mr. Hughes, the former wastewater treatment impoundments had been constructed in 1980 and the equalization tanks were constructed in the late 1980s/early 1990s. It is Mr. Hughes' understanding from his review of historic drawings and through discussions with past engineering consultants that the wastewater treatment impoundments and tanks were constructed in the same location as the former bottom and fly ash, metal hydroxide sludge, and coal ash accumulation areas.

The wastewater treatment impoundments were closed commencing in 1989, see E.C. Jordan. Clean Closure — Soils. 1990. Closure ofthe impoundments included 74 soil samples, installation of 8 groundwater monitoring wells (Wells OW-101 through OW-108), groundwater sampling and analysis, removal of impacted/stained soil beneath the liners ofthe impoundments, and submittal of closure documents to the MassDEP; see E.C. Jordan. Clean Closure - Soils. 1990. On December 17, 1991. the MassDEP approved the clean closure ofthe impoundments for both soils and groundwater.

Groundwater monitoring studies were conducted in the easterly portion ofthe property (and approximate location ofthe referenced accumulation areas) and in downgradient areas; see Addendum No. I to Groundwater Closure Performance Report ABB, 1997. As noted above, the referenced report was submitted to the MassDEP as part of Clean Closure ofthe impoundments. Further, groundwater samples obtained from three monitoring wells installed by GZA to evaluate conditions at the #2 fuel oil storage tanks (AOC 2), downgradient of the former coal ash accumulation area, were analyzed for PAHs; see Response Action Outcome Report RTN 3-17596. GZA. 2000. No PAHs were detected in groundwater at concentrations above the method detection limit. GZA also collected groundwater samples in the vicinity of Tank No. 3 (AOC 7), which is also downgradient of the former accumulation areas. A total of nine groundwater samples were analyzed for PAHs, which were not detected in any ofthe samples; see Phase II Comprehensive Site Assessment Report for Fuel Oil Tank No. 3, GZA. 1999.

Mr. Hughes was familiar with the operational history ofthe waste water treatment system through daily operational meetings, discussions with treatment plant operators, and review of compliance of documents. He was not aware of significant operational issues or non-conformances regarding discharges from the system to the environment. According to Mr. Hughes, the wastewater treatment system was decommissioned in 2007. During decommissioning ofthe treatment system, all tanks, pits and piping were drained, liquids and sediments were removed and disposed of off-site, and all components were pressure washed.

Given the completeness and thoroughness ofthe closure process, it is highly unlikely that any significant contamination related to the former accumulation areas and wastewater treatment system would have gone unidentified or unaddressed. Therefore, we conclude that groundwater in vicinity ofthe Former Wastewater Treatment Impoundments and Former Accumulation Areas is not known or reasonably suspected to he "contaminated" above appropriately protective risk-based "levels".

Southwest Courtyard Area: This area previously contained #6 fuel oil tanks and a sulfuric acid tank. Previous releases of #6 fuel oil

and sulfuric acid were reported, assessed, remediated and closed under the MCP. A release of #6 fuel oil was identified during response actions taken regarding a release of sulfuric acid. Monitoring wells were installed


Page 2.4

by RAM Environmental and by GZA, Inc.; see Final Phase 1 Initial Site Investigation Report RTN 3-13007. RAM Environmental. 1996 and the Phase II Comprehensive Site Assessment. RTN 3-13007. GZA, 1998.

The GZA Phase II Comprehensive Site Assessment (Phase II Report) references groundwater elevations measured in wells in the southwest courtyard as indicating groundwater fiow direction to be toward the south. The Phase II Report also indicates that regional groundwater fiow direction is toward the north and the Reserved Channel and that the groundwater in the area may be tidally influenced as well as influenced by building structures/foundations.

Examination ofthe groundwater elevations provided in the Phase II Report indicates that the flow direction is predominantly to the north/northwest towards the Reserved Channel. This flow direction is contraindicated only by the groundwater elevation in monitoring well MW-3. It should be noted that MW-3 is located at the southerly end ofthe release area and is located closer to the building than the other monitoring wells.

Petroleum concentrations attenuate in wells from the south (GZA-3) to the north (MW-l, GZA-2 and MW-3) lending further credence that groundwater flows to the north towards the Reserved Channel. Petroleum concentrations in the northerly wells (MW-l, MW-3 and GZA-1) are well below the MCP Method 1 GW-3 standards. Given that the site is approximately 800 feet from the Reserved Channel, groundwater concentrations would be expected to attenuate by an approximate 10-fold factor (see Table 4.4, MassDEP Policy #WSC-02-411) between the release area and the Reserved Channel. The calculated dilution factor further supports a finding that migration of contaminated groundwater is under control.

Furthermore, Exelon recently received a letter entitled "Notice of Audit Findings A UL Audit Inspection and Technical/Compliance Screenins Audits "from the MassDEP dated August 4, 2010 (see attached). The letter states the following:

"Based on the technical screening audit ofthe RAO, MassDEP is not directing you to undertake further response actions at this time in regard to the RAO."

Therefore, we conclude that this area has been properly assessed and addressed and meets all applicable standards under M. G. L. Chapter 21E and the MCP such that it poses no significant risk to human health or the environment. Groundwater flow direction is predominantly to the north/northwest towards the Reserved Channel (as expected based on regional groundwater flow characteristics). Further, #6 oil has limited solubility and mobility in the environment, and concentrations would be significantly diluted between the release site and the Reserved Channel.

Given these factors, we conclude that groundwater in vicinity ofthe Southwest Courtyard Area is not known or reasonably suspected to be "contaminated" above appropriately protective risk-based "levels".

Releases of Unknown Location: A total of 10 releases of unknown location have been identified at the Facility, nine of which involved either

#2 oil or #6 oil; see Draft RCRA Facilit\> Assessment, Mabbett and Associates, Inc. 2009. The remaining release involved approximately 600 gallons of magnesium. Fuel oil storage has occurred in three areas on the property: the #6 oil bulk storage tanks in the northeasterly corner, the #2 fuel oil tanks in the northcentral portion ofthe property, and former USTs in the southwestern portion ofthe property. The most likely locations for the fuel oil releases are in these areas ofthe property, all of which have been assessed. Magnesium storage occurred in the southwest courtyard area.

Throughout this time period, there is a history ofthe Facility proactively and responsibly identifying, reporting, assessing and addressing all environmental issues at the Facility in accordance with applicable environmental laws and regulations. The monitoring wells and soil borings installed on the property have


Page 2.5

evaluated soil and groundwater quality throughout the Facility over at least the last 25 years. The soil borings and wells were predominantly installed in areas of intensive industrial activities including the easterly portion of the property, the southwest courtyard area and in vicinity ofthe existing U6fuel oil bulk storage tanks. Assessment and response actions have also been taken in the vicinity ofthe #2 fuel oil storage tanks servicing the "L Street Jet" and at former transformers.

In eveiy case with the exception of Tank No. 3, the assessment and response actions taken have resulted in regulatory closure. In only one case have response actions taken for a release identified a previously unknown release and that release was subsequently assessed and closed under the Massachusetts Contingency Plan.

Therefore, we conclude that groundwater is not known or reasonably suspected to be "contaminated" from Releases of Unknown Location above appropriately protective risk-based "levels".

INDOOR AIR Potential indoor air impacts are typically associated with vapor intrusion of volatile compounds into occupied

structures. No volatile compounds have been identified in soil or groundwater at concentrations that are reasonably expected to affect indoor air. Therefore, we conclude that indoor air is not known or reasonably suspected to be "contaminated" above appropriately protective risk-based "levels ".

SURFACE SOIL The property is primarily covered with pavement and structures thereby limiting potential exposure to surface

soils. The portion ofthe easterly area ofthe property consists of gravel; this area was the location of the former accumulation areas and wastewater impoundments. Soil sampling completed as port ofthe impoundment closure did not identify any compounds in shallow soils at concentrations expected to pose a significant risk (see additional discussion under 'Subsurface Soils 'provided below). Therefore, we conclude that surface soil is not known or reasonably suspected to be contaminated above appropriately protective risk-based levels.

SURFACE WATER Releases of petroleum to surface waters (the Reserved Channel) have been previously documented at the

Facility. These releases were contained within the oil containment boom installed and maintained at the Facility. The record reflects a history of promptly reporting and addressing spills in accordance with the requirements of applicable laws and regulations including but not limited to the stringent standards ofM. GL. Chapter 21E and the accompanying Massachusetts Contingency Plan. Moreover, since 1993, all response actions at the Facility have been conducted under the direction and supervision of qualified Licensed Site Professionals, licensed by the Commonwealth of Massachusetts.

Releases to groundwater have also occurred (see discussion provided above). As noted, laboratory analyses of groundwater samples have not identified groundwater contaminated to a degree that could have a significant impact to surface water. Therefore, we conclude that surface water is not known or reasonably suspected to be contaminated above appropriately protective risk-based levels.

SEDIMENT Releases of petroleum to surface waters (the Reserved Channel) have been previously documented at the

Facility'. These releases were contained within the oil containment boom installed and maintained at the Facility'. The record reflects a history of promptly reporting and addressing spills in accordance with the requirements of applicable laws and regulations including but not limited to the stringent standards ofM. GL. Chapter 21E and the accompanying Massachusetts Contingency Plan. Moreover, since 1993, all response actions at the Facility have been conducted under the direction and supervision of qualified Licensed Site Professionals, licensed by the


Page 2.6

Commonwealth of Massachusetts. Releases to groundwater have also occurred (see discussion provided above). As noted, laboratory analyses of groundwater samples have not identified groundwater contaminated to a degree that could have a significant impact to sediments. Therefore, we conclude that sediment is not known or reasonably suspected to be contaminated above appropriately protective risk-based levels.

SUBSURFACE SOIL

Tank No. 3 : According to available records, in February 1993, ABB Environmental Services (ABB) completed

seventeen (17) soil borings (TP-I through TP-17) in the vicinity of Tank No. 3. Fourteen (14) ofthe soil borings were completed outside the steel containment dike and three M'ere completed inside the containment dike. After Tank No. 3 was emptied and cleaned. ABB completed six (6) soil boring (T-1 through T-6) inside the tank area. At each soil boring a sample was collected at the water table. Additionally, three (3) samples were taken from the gravel base materials immediately below the tank. Samples were analyzed for total petroleum hydrocarbons (TPH). Analytical results indicated levels of TPH in the soil ranging from 6 ppm to 214.500 ppm. TPH levels in soil borings T-1, T-2. T-f T-5, T-6, TP-7, TP-8 TP-9, TP-13, and TP-15 exceeded the applicable MassDEP Upper Concentration Limits (UCLs) for TPH under the MCP of 10,000 ppm. The extent and location of contamination is presented on the attached Site Plan prepared by ABB dated March 15, 1993.

On June 23 and 24, 1999 GZA and subcontractor GZA Drilling. Inc. completed eight (8) test borings (GZ-1 through GZ-8) in the vicinity of Tank No. 3. On June 25, 1999 GZA and subcontractor Geosearch, Inc. completed five (5) small diameter test borings(GP-l through GP-5) in the vicinity of Tank No. 3. A total of fourteen (14) soil samples were collected and sent for laboratory analysis. GZA 's Environmental Chemistry Laboratoty in Newton, Massachusetts, analyzed samples for extractable petj-oleum hydrocarbons (EPH) TPH, and target polynuclear aromatic hydrocarbons (PAHs). The soil analytical results indicated TPH concentrations of 7,100ppm in one soil sample, GP-1. This level exceeds the MCP Method 1 S-3/GW-3 standard for TPH, which is 5,000 ppm. Target PAH analytes were detected in nvo soil samples, GZ-5 and GP-5. The presence of PAH's was attributed to coal cinders observed in the sample. On July I, 1999 an additional sample was collected and submitted to the GZA Environmental Chemistry Laboratory for volatile petroleum hydrocarbons (VPH) analysis. Analytical results did not indicate VPH levels above applicable MCP Method 1 soil standards. Sample depths rangedfiom zero to eight feet below surface grade. The GZA subsurface exploration reaffirmed the previous delineation of contamination at the water table under Tank No. 3 and under the steel containment dike, see the attached Site Plan prepared by ABB Environmental Services, Inc. dated March 15, 1993.

GZA conducted a Method 3 Human Health and Ecological Risk Characterization for the Site, which is provided as Appendix G in the GZA Phase II - Comprehensive Site Assessment Report for Fuel Oil Tank No. 3, SITHE New Boston LLC. The risk characterization assumed that the current and reasonably foreseeable Site uses are the same. The risk characterization discussed the inaccessibility ofthe contaminants due to the contaminant location under Tank No. 3, the depth ofthe contaminants, and the depth of groundwater. Based on the risk characterization GZA concluded that all Substantial Hazards have been eliminated from the Site, and therefore the Site met the requirements of a Temporary Solution (Class C RAO) under the MCP. See GZA Phase I I - Comprehensive Site Assessment Report for Fuel Oil Tank No. 3, SITHE New Boston LLC dated August 9. 1999 (Appendix G).

On May 15, 2008, OHI Engineering, Inc. and subcontractor Geologic, Inc. completed ten (10) soil borings within the dike containment wall at various locations around the outside of Tank No. 3. Typically, the soils ranged from fine to medium sand with evidence of historic fill observed. A total of 10 soil samples were collected from the soil borings. The soil samples were stored in amber glass ja rs on ice and were delivered to Alpha Woods Hole Labs, a Massachusetts-certified independent laboratory. The soil samples were analyzed for


Page 2.7

extractable petroleum hydrocarbons (EPH) with target analytes using DEP-approved methodology. 5ee OHI Post Class C RAO Status Report September 2008.

In summary, residual #6 fuel oil from an historic release (RTN 3-4519) was discovered at various depths rangingfrom the suiface to approximately 10-12 below surface grade (bsg) in the vicinity of Tank No. 3. See attached Site Plan prepared by OHI Engineering. Previous analytical results indicate that UCLs for the TPH. C11-C22 aromatic hydrocarbon range and for the C19-C36 aliphatic hydrocarbon range were exceeded in borings T-1. T-2. T-f T-5, T-6, TP-7, TP-8, TP-9, TP-13, TP-15, B-3, B-7 andB-9 A Class C RAO has been filed with Mass. DEP in August 1999 in connection with RTN 3-4519. The Class C RAO indicates that a temporary solution has been achieved, ensuring the elimination of any substantial hazard and the identification; characterization and, to the extent feasible, elimination, control or mitigation of any source of OHM. The Class C RAO recommends no further action other than periodic monitoring. See GZA Class C Response Action Outcome Report for Fuel Oil Tank No. 3, SITHE New Boston LLC dated August 1999. The data recently collected by OHI corroborates the analytical soil data previously collected at the Site.

Releases affecting subsurface soil in the vicinit}' of Tank No. 3 have occurred. However, risk analysis previously prepared and submitted to the MassDEP indicates that there is no risk of substantial harm given current site conditions.

Former Wastewater Treatment Impoundments and Former Accumulation Areas: The wastewater treatment impoundments were closed commencing in 1989. Closure ofthe impoundments

included 74 soil samples, installation of 8 groundwater monitoring wells (Wells OW-101 through OW-108), groundwater sampling and analysis, removal of impacted/stained soil beneath the liners ofthe impoundments, and submittal of closure documents to the MassDEP. On December 17, 1991, the MassDEP approved the clean closure ofthe impoundments for both soils and groundwater.

Coal and coal ash residues were identified in soil borings conducted as part ofthe impoundment closure; see Closure Soils Report E. C Jordan, 1990. As shown on Table I and Table 2 ofthe Closure Soils Report E.C. Jordan, 1990. certain metals and polycyclic aromatic hydrocarbons (PAHs), likely associated with the former accumulation areas, were detected in a portion ofthe soil samples analyzed during impoundment closure activities. Accordingly, the metals and PAHs were subjected to a risk assessment; see Closure Soils Report - Addendum #1. EC. Jordan. 1990 and were shown to pose no significant risk

Comparison ofthe mean concentrations of detected PAHs and metals in the soil samples to MassDEP's Technical Update Background Levels of Polycyclic Aromatic Hydrocarbons and Metals in Soil indicates that concentrations of metals and PAHs at the facility are generally consistent with typical urban fill. Thus, we conclude that the historic former fiy and bottom ash accumulation area (SWMU 3), the former metal hydroxide sludge accumulation area (SWMU 4), the former coal ash accumulation area (SWMU-8) and the former waste water treatment system (SWMU 12) have not impacted soils at the site at levels beyond those typically seen in urban fill throughout the Commonwealth of Massachusetts or to a degree that would pose a significant risk

Therefore, we conclude that subsurface soil in vicinity of the former wastewater tteatment impoundments and former accumulation areas is not known or reasonably suspected to be contaminated above appropriately protective risk-based levels.

Southwest Courtyard Area: This area previously contained #6 fuel oil tanks and a sulfuric acid tank Previous releases of #6 fuel oil

and sulfuric acid were reported, assessed, remediated and closed under the MCP. A release of 06 fuel oil was identified during response actions taken regarding a release of sulfuric acid. Monitoring wells were installed by RAM Environmental and by GZA, Inc.; see Final Phase I Initial Site Investigation Report RTN 3-13007.

Current Human Exposures Under control Environmental Indicator (EI) RCRIS code (CA725)

Page 2.8

RAM Environmental, 1996 and the Phase II Comprehensive Site Assessment RTN 3-13007. GZA, 1998. Institutional controls consisting of an Activity and Use Limitation (AUL) filed at the Suffolk County Registry of Deeds have been placed on this area to control potential human exposure to subsurface soil. The A UL extends over an area of approximately 5,670 square feet Within the A UL area, the following restrictions apply:

• The area may not be used as a residence, children's school, outdoor playground, outdoor children's recreation area or other such use where a child may come into direct contact with soil;

• Activities and/or uses which involved the removal of existing soil, gravel or pavement cover of building foundation from the A UL area and/or disturbance ofeontaminated soil or groundwater without the prior development of a Soil "Management Plan by an LSP, and for longer-term project in excess of six month, the prior development and implementation of a Health and Safety Plan.

Therefore, we conclude that subsurface soil in vicinity ofthe southwest courtyard area is not known or reasonably suspected to be contaminated above appropriately protective risk-based levels.

Releases of Unknown Location: A total of 10 releases of unknown location have been identified at the Facility, nine of which involved either

#2 oil or #6 oil. The remaining release involved approximately 600 gallons of magnesium. Fuel oil storage has occurred in three areas on the property: the #6 oil bulk storage tanks in the northeasterly corner, the it2fuel oil tanks in the northcentral portion ofthe property, and former USTs in the southwestern portion ofthe property. The most likely locations for the fuel oil releases are in these areas ofthe property, all of which have been assessed. Magnesium storage occurred in the southwest courtyard area. No information has been compiled suggesting that the releases of unknown location could have affected subsurface soils to a degree known or reasonably suspected to be "contaminated" above appropriately protective risk-based "levels.

OUTDOOR AIR Potential outdoor air impacts are typically associated of volatile compounds discharging to outdoor air or to.

potentially contaminated dust generated during construction activities. No volatile compounds have been identified in soil or groundwater at concentrations that could affect outdoor air and no construction activities are planned that could result in significant dust exposures. Therefore, we conclude that outdoor air is not known or reasonably suspected to be "contaminated" above appropriately protective risk-based "levels".


Page 3

3. Are there complete pathways between "contamination" and human receptors such that exposures can

be reasonably expected under the current (land- and groundwater-use) conditions?

Summary Exposure Pathway Evaluation Table

Potential Human Receptors (Under Current Conditions) Contaminated Media Residents Workers Day-Care Construction Trespassers Recreation Food'

Groundwater — ^ ^ ^

Soil (nuffncc, a.a.. <2 ft)

Surface Vifalor

Sediment

Soil (subsurface, e.g., >2 ft) N0_ NO NO NO' NO NO NO

Insfructions for Summary Exposure Pathway Evaluation Table:

1. Strike-out specific Media including Human Receptors' spaces for Media which are not "contaminated" as identified in #2 above.

2. enter "yes" or "no" for potential "completeness" under each "Contaminated" Media - Human Receptor combination (Pathway).

* See Rationale and References, below. Note: In order to focus the evaluation to the most probable combinations some potential "Contaminated" Media - Human Receptor combinations (Pathways) do not have check spaces (" "). While these combinations may not be probable in most situations they may be possible in some settings and should be added as necessary.

X If no (pathways are not complete for any contaminated media-receptor combination) -skip to #6, and enter "YE" status code, after explaining and/or referencing condition(s) in-place, whether natural or man-made, preventing a complete exposure pathway from each contaminated medium (e.g., use optional Pathway Evaluation Work Sheet to analyze major pathways).

If yes (pathways are complete for any "Contaminated" Media - Human Receptor combination) - continue after providing supporting explanation.

If unknown (for any "Contaminated" Media - Human Receptor combination) - skip to #6 and enter "IN" status code.


Institutional controls are in place and maintained to limit access to the propert}' and for securit}' purposes thereby limiting potential exposure to impacted soil. The property is surrounded with an intact chain-link fence and

^ Indirect Pathway/Receptor (e.g., vegetables, fruits, crops, meat and dairy products, fish, shellfish, etc.)


Page 3.1

entr}> to the proper!)' is controlled. A securit}' guard is stationed at the Site 24 hours per day. seven da}'s per week, 365 da}'s per year and the Site is protected with surveillance cameras that operate24 hours per day, seven days per week. 365 days per year. Site workers and visitors are required to undergo Exelon Safety Training prior to accessing the Site. The potential for human exposure to impacted soil by trespassers and visitors is minimal

According to the City of Boston Zoning Regulations, the property is located within the South Boston Maritime Economy Reserve Subdistrici, which is one of six working waterfront subdistricts in the Dorchester Bay/Neponset River Waterfront The working waterfront districts were established in order to "... maintain, foster, and promote maritime economy within the Cit}' of Boston; to provide for light manufacturing water-dependent uses; to preserve sites for maritime-dependent industrial uses along the waterfront consistent with applicable state policy and the needs ofthe maritime industry; to create opportunities for manufacturing and business on the waterfront... ". The Facility is not currently used for residential purposes.

Institutional controls consisting of an Activity and Use Limitation (A UL) filed at the Suffolk County Registiy of Deeds have been placed on the Southwest Courtyard area to control potential human exposure to subsurface soil. The A UL extends over an area of approximately 5,670 square feet. Within the A UL area, the following restrictions apply:

• The area ma}' not be used'as a residence, children's school outdoor pla)'ground, outdoor children's recreation area or other such use where a child may come into direct contact with soil;

• Activities and/or uses which involved the removal of existing soil, gravel or pavement cover of building foundation from the A UL area and/or disturbance ofeontaminated soil or groundwater without the prior development of a Soil "Management Plan by an LSP. and for longer-term project in excess of six month, the prior development and implementation of a Health and Safety Plan.

Access to potentially impacted subsurface soil at the Facility is restricted by buildings, pavements and other surface structures, which act as physical barriers to exposure to potentially impacted subsurface soils and by deed restriction in the Southwest Court}>ard area. Any construction activities that may take place at the Facility that could include exposure to potentially impacted subsurface soil have been and will continue to be conducted in accordance with health and safety standards put in place by Exelon New Boston LLC. These standards include Exelon Safety Training and a Soils Management Plan for excavation activities, which limits potential exposure qf construction workers to impacted soils; see OHI Soil Management Plan dated October 15. 2008.

Therefore, we conclude that there are no complete pathways for human exposure.


Page 4

Can the exposures from any ofthe complete pathways identified in #3 be reasonably expected to be "significant"'' (i.e., potentially "unacceptable" because exposures can be reasonably expected to be: 1) greater in magnitude (intensity, frequency and/or duration) than assumed in the derivation ofthe acceptable "levels" (used to identify the "contamination"); or 2) the combination of exposure magnitude (perhaps even though low) and contaminant concentrations (which may be substanfially above the acceptable "levels") could result in greater than acceptable risks)?

If no (exposures can not be reasonably expected to be significant (i.e., potentially "unacceptable") for any complete exposure pathway) - skip to #6 and enter "YE" status code after explaining and/or referencing documentation justifying why the exposures (from each ofthe complete pathways) to "contamination" (identified in #3) are not expected to be "significant."

If yes (exposures could be reasonably expected to be "significant" (i.e., potentially "unacceptable") for any complete exposure pathway) - continue after providing a description (of each potentially "unacceptable" exposure pathway) and explaining and/or referencing documentation justifying why the exposures (from each ofthe remaining complete pathways) to "contamination" (identified in #3) are not expected to be "significant."

If unknown (for any complete pathway) - skip to #6 and enter "FN" status code.

Rationale arid Reference(s):

"* If there is any question on whether the identified exposures are "significant" (i.e., potentially "unacceptable") consult a human health Risk Assessment specialist with appropriate education, training and experience.


Page 5

Can the "significant" exposures (identified in #4) be shown to be within acceptable limits?

If yes (all "significant exposures have been shown to be within acceptable limits) -continue and enter "YE" after summarizing and referencing documentation justifying why all "significant" exposures to "contamination" are within acceptable limits (e.g., a site-specific Human Health Risk Assessment).

If no (there are current exposures that can be reasonably expected to be "unacceptable") • continue and enter "NO" status code after providing a description of each potentially "unacceptable exposure.

If unknovm (for any potentially "unacceptable" exposure) - continue and enter "IN" status code.



Page 6

Check the appropriate RCRIS status codes for the Current Human Exposures Under Confrol EI event code (CA725), and obtain Supervisor (or appropriate Manager) signature and date on the EI detemiination below (and attach appropriate supporting documentation as well as a map ofthe facility):

YE YE - Yes, "Current Human Exposures Under Control" has been verified. Based on a review ofthe information contained in this El Determination, "Current Human Exposures" are expected to be "Under Confrol" at the Exelon New Boston Station facility, EPA ID # MAR000010702 (Former EPA ID # : 000845420), located at 776 Summer Sfreet, Boston, MA 02127 under current and reasonably expected conditions. This determination will be re-evaluated when the Agency/State becomes aware of significant changes at the facility.

NO - "Current Human Exposures" are NOT "Under Control."

IN - More information is needed to make a detemiination.

Completed by: OHI Engineering, Inc.

Date: 9/29/2010

Supervisor: (print) rT>y(gf J'r C ^ & ^ (tide) C4if/ ' /C^/^^ Or^r-AiAt Jf/^-^ (EPA Region or State) ^ / i » - .x_

Locations where References may be found: Massachusetts Department of Environmental Protection -Northeast Regional Office, Exelon New Boston Facility, Exelon New Boston office in Medway, MA

GZA GeoEnvironmental. Inc. Phase II - Comprehensive Site Assessment Report for Fuel Oil Tank No. 3. SITHE New Boston LLC dated August 9. 1999 GZA GeoEnvironmental. Inc. Class C Response Action Outcome Report for Fuel Oil Tank No. 3, SITHE New Boston LLC dated Ausust 9. 1999 GZA GeoEnvironmental, Inc., Risk Characterization, SITHE New Boston. LLC dated Ausust 1999. GZA GeoEnvironmental .Inc. Periodic Evaluation ofthe Temporar\> Solution Fuel Oil Tank No. 3, 776 Summer Street. Boston, MA dated November 2004 GZA GeoEnvironmental. Phase II Comprehensive Site Assessment, RTN 3-13007. 1998. GZA GeoEnvironmental. Response Action Outcome Report RTN 3-17596, 2000 OHI Engineering, Inc. Post Class C RAO Status Report. September 2008. OHI Engineering, Inc. Post Class C RAO Status Report. March 2009. OHI Engineering. Inc. Post Class C RAO Status Report September 2009 OHI Engineering. Inc. Final Periodic Evaluation ofthe Temporary Solution, November 2009 OHI Engineering, Inc. Post Class C RAO Status Report September 2010 OHI Engineering. Inc., Soil Management Plan, October 2008 E. C Jordan. Inc., Clean Closure Report-Soils, 1990 E.C. Jordan, Inc.. Addendum No. 1 Clean Closure Report - Soils, 1990 RAM Environmental. Final Phase I Initial Site Investigation Report RTN 3-13007. 1996 ABB. Addendum No. 1 to Groundwater Closure Performance Report, 1997


Page 6.1

Mabbett and Associates. Inc., Draft RCRA Facility Assessment, 2009 Mass DEP. Notice of Audit Findings A UL Audit Inspection and Technical/Compliance Screening Audits, August 2010

Contact telephone and e-mail numbers

For OHI (name) James R. Borrebach (phone #) 508-339-3929 (e-mail) iborrebach(a).ohiengineering.com

FINAL NOTE: THE HUMAN EXPOSURES El IS A QUALITATIVE SCREENING OF EXPOSURES AND THE DETERMINATIONS WITHIN THIS DOCinVIENT SHOULD NOT BE USED AS THE SOLE BASIS FOR RESTRICTING THE SCOPE OF MORE DETAILED (e.g., SITE-SPECIFIC) ASSESSMENTS OF RISK.

Facility Name: EPA1D#: City/S'tate:

CURRENT HUMAN EXPOSURES UNDER CONTROL (CA 725)

f.evel

IN NO

> • •

N

N

Y

' r

YE

tr a i UC I WkSS«>iJGaTS »V TEWISPOAinON WTHQAITY (1V(>Enn-

•~i TiiUmiWiTi TMtftfTi'M [ r i~ n n n l^ •^^ f» l^J l l ^^•^^^ .CT(r^n, r i fT- l^ r , - |^ l r^ -^^mr^ lw^^ l l^ ,T l^ lJ lw^^W7. j l«<» l^^^^v^J^mr- -T l^g^g^

SWMU-11-FORMER ASH SILO

•SWMU-1 & 2 FORMER SURFACE IMPOUNDMENTS

.SWMU-9 ORIGINAL WASTEWATER TREATMENT POND

SWMU-10 FORMER EARTHEN WASTEWATER POND

SWMU-3 FORMER ASH ACCUMULATION AREA

SWMU-4 FORMER METAL HYDROXIDE SLUDGE ACCUMULATION AREA

SWMU-8 FORMER ASH ACCUMULATION AREA

SWMU-12 FORMER WASTEWATER TREATMENT SYSTEMS

^ G U ^ u • L - 2 IS BASED ON DRAWING BY BOSTON EDISON, ENGINEERING SERVICES GROUP, NAMED, NEW BOSTON ASSET ALLOCATION GENERAL PLAN. ;)ATED. (NO DATE INDICATED ON PLAN)

LEGEND SWMU = SOLID WASTE MANAGEMENT UNIT

SITE BOUNDARY

>00\WORK\RCRA RFA\Srth« N««r 8or ton \SHh« New Bo l t on i l t a plan L - 2 naw1.d«« - Stt« Rguro L - 2 - Mar. 06 . 2008 8:58f lm -

NO. DATE DESCWPnON URN CHK APP REViaON

EXELON NEW BOSTON ELECTRIC GENERATING STATION

776 SUMMER iSTREET SOUTH BOSTON. MASSACHUSETTS

Mabbett & Associates Envlr«ntiKv\tal Coniulunb & Efi^l nccn

EXELON NEW BOSTON ELECTRIC GENERATING

STATION SWMU MAP

DRAMLWA lAPPROVED J G ISCAli NOT TO SCAt£

ow&Na

L-2 PROJ. Na 7051012.001

i]a

^iQTES••

AOC-7 RELEASE TRACKING NUMBER 3-04519

AOC-6 No. 6 FUEL OIL PIPING TRANSFER METER PIT

AOC-10 No. 6 F U a OIL PIPEUNE

'.OCATION INFORMATION FOR RELEASES IDENTIFIED UNDER \0C-1 WAS NOT PROVIDED IN THE FILE MATERIAL.

M" "il RGUKu 1^3 IS BASED ON DRAWING BY BOSTON EDISON. rNQNEERING SERVICES GROUP. NAMED, NEW BOSTON ASSET ALLOCATION GENERAL PLAN. OATED, (NO DATE INDICATED ON PLAN)

AOC-5 PCB RELEASE

AOC-9 FORMER UNIT #2 TRANSFORMER AREA

AOC-3 RELEASE TRACKING NUMBER 3-22165

AOC-4 RELEASE TRACKING NUMBERS 3-12817, 3-14575, 3-26342 AOC-8 RELEASE TRACKING NUMBER 3-12817/3-13007

LEGEND AOC = AREA OF CONCERN

SITE BOUNDARY

• <J30\W0RK\RCRA RFA\Stlhe N m Bo«ton\SI(ha Now Beaton «lte p lon L - 3 AOC Mop.dwg - Stt« Flfli jr« L - 3 - Mor. 0 6 . J009 9 :49am - dja

NO. PATE DESCWPTMN \m CHK APP REVISGN

EXELON NEW BOSTON ELECTRIC GENERATING STATION

776 SUMMER STREET SOUTH BOSTON, MASSACHUSETTS

Mabbett & Associates Env1r«nnK»tnr ConiMlunb £ Erglnocn

DRASW DJA |APPRO\a) JRC

AREAS GF CONCERN MAP

jSCAU NOT TO SCAL£

DW5.Na

L-3 PfiOJ. NO. 70S1012.001

rdms docid 109084 - semspub.epa.gov · current human exposures under control environmental...

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