Global Operations, Environment, Health & Safety

159 Plastics Avenue Pittsfield, MA 01201

September 30, 2016

Mr. Richard Fisher (OSRR07-1) U.S. Environmental Protection Agency, Region I EPA New England (MC HBO) 5 Post Office Square - Suite 100 Boston, MA 02109-3912

Re: GE-Pittsfield/Housatonic River Site (the “Site”) Evaluation of NAPL Recovery Systems – Proposed Activities Groundwater Management Areas 1 and 3 (GECD310 and GECD330)

Dear Mr. Fisher:

On August 30, 2016, the General Electric Company (GE) submitted the following documents to the United States Environmental Protection Agency (EPA):

“Long-Term Trend Evaluation Report – Spring 2016” for Groundwater Management Area (GMA) 1, which summarized groundwater and non-aqueous-phase liquid (NAPL) monitoring and recovery activities during the Spring 2016 period.

“Groundwater and NAPL Monitoring Interim Report – Spring 2016” for GMA3, which summarized groundwater and NAPL monitoring and recovery activities during the Spring 2016 period.

Since the onset of NAPL recovery at the Site over 35 years ago, GE has continuously monitored, assessed, upgraded, expanded, and optimized its NAPL recovery efforts; several of these activities have been conducted in accordance with the applicable requirements of the October 2000 Consent Decree (CD) for the Site. Over this time, there has been extended success in: 1) removing NAPL from the Site (to varying degrees depending on the specific recovery system), 2) reducing the overall extent and quantity of NAPL that remains within the Site, and 3) maintaining compliance with the applicable Performance Standards established in the CD.

For certain of the systems, the NAPL recovery rates have diminished over time to the point where limited NAPL recovery is currently being realized. To potentially increase NAPL removal from these recovery systems (if practicable to do so), each of the above reports indicated that, on or before September 30, 2016, GE would submit a proposal to EPA outlining specific actions to further assess/maximize light NAPL (LNAPL) and dense NAPL (DNAPL) recovery at GMA 1, and to maximize LNAPL recovery at GMA 3.

The remainder of this proposal summarizes the objectives, scope, and schedule for further evaluation of the certain existing NAPL recovery systems within GMA 1 and GMA 3. These include:

North and South Caissons in East Street Area 1 (GMA 1)

Newell Street Area II (GMA 1)

Recovery Well GMA3-17 (GMA 3)

GE OneEHS

Richard Fisher September 30, 2016

Page 2 of 6

1. Evaluation Objectives

In accordance with Technical Attachment H of the CD, GE is obligated to assess the recovery systems for each NAPL area at the Site and propose enhancements as necessary to meet the long-term goal of maximizing NAPL recovery and eliminating mobile NAPL. In addition to that Performance Standard, this proposal considers several recent EPA comments regarding the recovery systems listed above. The EPA comments, and subsequent follow-up/updates to those comments, are summarized below.

GMA 1

East Street Area 1 (North and South Recovery Systems):

EPA Comment

EPA’s conditional approval of the “Groundwater Management Area 1, Monitoring Event Evaluation Report- Fall 2014” (letter dated May 22, 2015) stated: “Following the maintenance of the East Street Area 1 NAPL recovery system in November 2014, the monthly automated recovery volume continues to be zero as given in the monthly reports. If the lack of automated LNAPL recovery continues through June 2015, in the next report GE shall propose a measure or measures which can be implemented in the Fall of 2015 in an attempt to increase LNAPL recovery in this area.”

Response / Update

Related to this EPA comment, GE’s “Long-Term Monitoring Program Monitoring Event Evaluation Report – Spring 2015 for Groundwater Management Area (GMA) 1” indicated that “Given the low permeability of the soil in this area and the relatively small amount of LNAPL that appears to be remaining in the area, the ability to recover that small amount of NAPL is limited. Thus, while the maintenance activities do not appear to have had an impact on automated recovery at the Northside Caisson, additional measures conducted at the caisson are not warranted. GE will continue to monitor the presence of NAPL in nearby wells and, if necessary, propose modifications to the automated recovery system.”

Newell Street Area II:

EPA Comment

EPA’s May 22, 2015 conditional approval of the “Groundwater Management Area 1, Monitoring Event Evaluation Report- Fall 2014”, submitted on February 27, 2015, stated that, “…DNAPL thicknesses in the 3 recovery wells within Newell Street Area remained fairly consistent yet greater than 50% of the automated monthly recoveries were zero. Immediately following replacement of the 90 degree elbows and verification that all DNAPL lines are no longer obstructed, GE shall implement an optimization testing period with adjustments to the dwell and pump times in order to document the most effective operational parameters for the system.” Further and more directed to this Proposal, “If repair and optimization do not improve recoveries of the DNAPL as indicated by the DNAPL thickness measurements, then GE shall consider significant upgrades to the system, such as redevelopment of existing wells or the potential installation of new wells, in an effort to increase recovery to achieve a yield that might be expected based on the DNAPL thickness and historical DNAPL recovery rates.”

Response / Update

In response, GE’s “Long-Term Monitoring Program Monitoring Event Evaluation Report – Spring 2015 for Groundwater Management Area (GMA) 1” indicated that “…DNAPL removal rates have decreased significantly and may be reaching “de minimis” levels.” and that, , “GE will continue to evaluate future DNAPL thickness measurements and recovery rates to further assess the impacts of the maintenance and optimization activities.”

G:\GE\GE_Pittsfield_CD_GMA_1\Reports and Presentations\0931611324 NAPL Proposal GMA 1 and GMA 3.docx

Richard Fisher September 30, 2016

Page 3 of 6

GMA 3

Recovery Well GMA3-17

EPA Comment

EPA’s conditional approval (letter dated April 13, 2016) for the “Groundwater Management Area 3, Long-Term Monitoring Program, Monitoring Event Evaluation Report - Fall 2015” stated: “…For recovery well GMA3-17, a comparison of past recovery and nearby LNAPL thicknesses indicates that recovery is being less efficient than it was historically, and EPA feels the well need to be optimized to maximize recovery as required by the SOW.” EPA notes that, “while LNAPL thicknesses in the immediate area around GMA3-17 remain consistent, recovery from this well has slowed to low levels. Since the skimmer system was found to be operating normally and maintenance efforts have not restored recovery to historical levels, GE shall evaluate other specific measures to satisfy the long-term goal of maximizing recovery and shall propose such measures to EPA for review and approval in the next monitoring report. Such measures shall consist of more than further maintenance and shall consider replacing the well pack for the GMA3-17 screen.

Response / Update

Specific to this EPA comment, GE’s “Groundwater and NAPL Monitoring Interim Report – Spring 2016 for Groundwater Management Area (GMA) 3” indicated that there was a measureable increase in LNAPL recovery following general maintenance and screen cleaning activities conducted in September 2015 and that LNAPL removal increased from 0.8 gallons over a six-month period in 2015 to approximately 2.7 gallons in 2016 during the same period.

The remainder of this proposal identifies field activities that will support further evaluation of these recovery systems. The proposed activities focus on the collection of information concerning the relative mobility of LNAPL and DNAPL in each area.

2. Proposed NAPL Assessment Activities

The physical presence of NAPL in the environment is not always a reliable predictor of successful or practicable NAPL recoverability. This is especially true during the latter stages of system operation, when the lateral and vertical extent, mobility, and recoverability of NAPL has diminished. For much of the past decade, the Interstate Technology and Regulatory Council (ITRC) and ASTM (2007, 2011) have used LNAPL transmissivity as an indicator of LNAPL recoverability, and specifically the “endpoint” of practicable NAPL recovery. Transmissivity is a measure of how much and how quickly LNAPL can flow through soil. It is a metric that incorporates NAPL- and soil-specific properties into a single parameter that, with respect to assessing LNAPL mobility and recoverability, is more reliable than in-well LNAPL thickness.

The use of transmissivity test data in LNAPL system evaluations has been endorsed at the state and national level. Specifically, the Massachusetts Department of Environmental Protection (MDEP) has prepared a document entitled “Light Non-Aqueous Phase Liquids (LNAPL) and the MCP: Guidance for Site Assessment and Closure” (MDEP LNAPL Guidance) for consideration at sites regulated by the Massachusetts Contingency Plan (MCP). That guidance document provides details and discussion related to the use of transmissivity testing as part of an overall demonstration of LNAPL recovery evaluations, including the feasibility of continued system operation

Consistent with the regulatory guidance identified above, LNAPL transmissivity testing and DNAPL recoverability testing is proposed for select locations within GMA 1 and GMA 3.

G:\GE\GE_Pittsfield_CD_GMA_1\Reports and Presentations\0931611324 NAPL Proposal GMA 1 and GMA 3.docx

Richard Fisher September 30, 2016

Page 4 of 6

GMA 1

LNAPL Mobility Assessment

To further assess: 1) the relative mobility of the LNAPL in East Street Area 1, and 2) whether an increased rate of LNAPL recovery can be practicably recovered within a reasonable timeframe, testing of LNAPL transmissivity in select monitoring and recovery wells is proposed. Evaluation of NAPL transmissivity by manual skimming test per ASTM E2856-13 involves periodic LNAPL removal to maintain at least 75% of full LNAPL drawdown. Target test areas in GMA1 include locations where LNAPL thicknesses are relatively stable and exceed approximately 0.3 feet, and are not under the influence of an active recovery system or significant water table fluctuations. A baildown test per ASTM E2856-13 may be considered where LNAPL thickness exceeds 0.5 feet and the LNAPL appears relatively mobile. In light of the above, transmissivity testing is proposed for the following wells, as shown on Figure 1:

East Street Area 1 – North (in proximity to the North Caisson): Wells 105 and 106

East Street Area 1 – South (in proximity to the South Caisson): Well ESA1S-45

If necessary, active operations within the caissons will be temporarily suspended to facilitate the transmissivity testing.

DNAPL Mobility Assessment

For Newell Street Area II, where DNAPL accumulations have been observed, a preliminary review of well logs, top of till/silt interpretations, and historical top of DNAPL elevation data was conducted. Wells N2SC-01I, N2SC-01IR, N2SC-03I, N2SC-03IR, and N2SC-13I were found to have measured DNAPL thicknesses greater than the depth of the constructed well sump, indicating potential DNAPL presence in and connection with the surrounding formation. Therefore, additional DNAPL mobility testing is proposed as a next step in evaluating DNAPL recovery in this area.

While no industry-wide standards or test methods currently exist, the same principles of LNAPL mobility and recoverability are appropriate to evaluate DNAPL mobility (Nelson and Smith 2016). Testing will be subject to the same pre-test conditions (e.g., stability of NAPL thickness and no influence from an active recovery system) and testing methods (e.g., baildown testing) as those proposed for LNAPL assessment. Also, the top of the DNAPL must be in communication with (through the screen and filter pack) the surrounding soil formation. If needed, active system operations will be suspended prior to the test. As shown on Figure 2, the following five locations have been identified for future testing:

Newell Street Area II: Wells N2SC-03I, N2SC-03I(R), N2SC-1I, N2SC-1I(R), and N2SC-13I

GMA 3

LNAPL Mobility Assessment

Similar to GMA 1, GE proposes transmissivity testing to supplement the available information in the vicinity of GMA3-17 and to understand whether additional LNAPL removal in this area is practicable. As shown on Figure 3, in addition to Recovery Well GMA3-17, the following 11 locations been identified for testing:

Wells 51-05R, 51-08, 51-15, 51-17, 51-19, 51-21, 59-01, 59-03, 59-07, GMA3-10, and GMA3-12.

LNAPL recovery tests performed in May 2007 for certain wells within GMA 3 were conducted in manner that closely replicates the procedures of a manual skimming test (ASTM E2856-13) and may provide reasonable estimates of LNAPL transmissivity from that time. As such, the May 2007 data may provide a reference point for comparison to the results of the proposed transmissivity testing.

G:\GE\GE_Pittsfield_CD_GMA_1\Reports and Presentations\0931611324 NAPL Proposal GMA 1 and GMA 3.docx

Richard Fisher September 30, 2016

Page 5 of 6

3. Evaluation of Testing Results

The results of the testing described above will assist in determining if LNAPL and DNAPL near the active

recovery systems is mobile and amenable to further removal, either as part of the existing system

operations or in response to future system enhancement{s). Initially, the transmissivity data will be evaluated against the absolute value of LNAPL transmissivity. ITRC {2009) proposes that an LNAPL transmissivities of 0.1 to 0.8 ft2/day represent the limit of practicable LNAPL recovery. This is reinforced by the MDEP LNAPL Guidance, which indicates that transmissivity results less than 0.8 ft2/day suggest that the continued operation of a LNAPL recovery system is not feasible.

The transmissivity data will also be incorporated into an overall evaluation of potential NAPL recoverability that will consider multiple lines of evidence. For example, spatial and temporal NAPL thicknesses and recovery data, hydrogeologic conditions in areas where measured NAPL is currently present, and details related to the current system operations will be considered.

Depending on the results of the additional testing , and the incorporation of those results into the overall evaluation of the NAPL recovery systems, GE will prepare a proposal for future NAPL recovery activities. These may include general system maintenance, well rehabilitation or replacement, unchanged operations, changes to water pumping rates, and/or pulsed operation. Alternatively, it may be determined that in one or more areas that remaining NAPL is not recoverable such that active recovery is no longer practicable.

Following EPA approval, GE will implement the proposed activities as part of its ongoing NAPL monitoring

activities, and will provide a summary of the results and proposal(s) related to future NAPL recovery operations in the GMA 1 Long-Term Monitoring Program, Monitoring Event Evaluation Report - Spring 2017, and the GMA 3 Long-Term Monitoring Program Evaluation Report - Spring 2017.

Please contact me with any questions regarding the information provided herein.

Sincerely,

i 'c/iµ/ {(;{j&ffll,I)

Richard W. Gates Senior Project Manager - Environmental Remediation

cc: Dean Tagliaferro, EPA* Barbara Landau, Noble & Wickersham* Timothy Conway, EPA* Richard Nasman, Berkshire Gas Christopher Ferry, ASRC Primus* Jack Yablonsky, Berkshire Gas Scott Campbell , Avatar* lshwar Muraka, lsh, Inc. Michael Gorski, MDEP* David Langseth, Gradient Corporation Eva Tor, MDEP* Erin Cullen, GE Corporate Properties and Jane Rothchild, MDEP* Services Operations John Ziegler, MDEP* Roderic McLaren, GE* Karen Pelto, MDEP* Matthew Calacone, GE* Nancy E. Harper, MA AG* James Bieke, Sidley Austin Robert Leitch, USAGE* James M. Nuss, LSP, Arcadis Nate Joyner, Pittsfield Dept. of Community Development* Public Information Repositories Corydon Thurston, Executive Director, PEDA* GE Internal Repository James Gagnon, O'Reilly, Talbot & Okun*

* submitted electronically

G:\GE\GE_Pittsfteld_CO_GMA_ 1\Reports and Presentations\0931611324 NAPL Proposal GMA 1 and GMA 3.docx

Richard Fisher September 30, 2016

Page 6 of 6

References:

ASTM. 2007. Standard Guide for Development of Conceptual Site Models and Remediation Strategies for Light Nonaqueous-Phase Liquids Released to the Subsurface. ASTM E2531-06. www.astm.org/Standards/E2531.htm

ASTM. 2011. Standard Guide for Estimation of LNAPL Transmissivity. ASTM E2856-13. www.astm.org/Standards/E2856.htm

EPA (Environmental Protection Agency). 2005. A Decision-Making Framework for Cleanup of Sites Impacted with Light Non-Aqueous Phase Liquids (LNAPL). EPA-542-R-04-011. EPA Remediation Technologies Development Forum, NAPL Cleanup Alliance. www.rtdf.org/public/napl/default.htm

ITRC (Interstate Technology & Regulatory Council). 2009a. Evaluating Natural Source Zone Depletion at Sites with LNAPL. LNAPL-1. Washington, D.C.: Interstate Technology & Regulatory Council, LNAPLs Team. www.itrcweb.org

ITRC. 2009b. Evaluating LNAPL Remedial Technologies for Achieving Project Goals. LNAPL-2. Washington, D.C.: Interstate Technology & Regulatory Council, LNAPLs Team. www.itrcweb.org

Massachusetts Department of Environmental Protection. 2016. Light Nonaqueous Phase Liquids (LNAPL) and the MCP: Guidance for Site Assessment and Closure. Policy #WSC-16-450.

Nelson, T and J. Smith (Arcadis). 2016. DNAPL Baildown Testing and Analysis. Tenth International Conference on Remediation of Chlorinated and Recalcitrant Compounds. Palm Springs, California; May 22-26.

GE OneEHS

http:www.itrcweb.orghttp:www.itrcweb.orgwww.rtdf.org/public/napl/default.htmwww.astm.org/Standards/E2856.htmwww.astm.org/Standards/E2531.htm

::; a. ... ';!

~ ~ C>

ci

§ w

a.

(.) "' ___ ..__ __,----· .... ...,..., ~ :::, "

~ .:U..., "' ~ --------· I --w -----------------;;~ I

~08A~ I 69 I ~ NORTH SIDE RECOVERY I __d-J31R I" SYSTEM" w g "' a.

Xo7 ~ T I ---------,_____ • l T -;R1 2s.--• § () _ ___J,,_ ~ A1N ,/ 25 , --- ;;:sy: , STREET a: :::, ~ S1-08R= ESA1S 46 ~ Caisson- EA ST ESA1S-47"'w

i ESA1N-PZ-1 ESA1 :c ts1-13R w .... ESA1S-33 + 0

1----+-- +--- SOUTHSIDE"' ::; ESA 1S-l2ROIJSA1S-72 ESA 1S- 75 RECOVERY 0d SYSTEM"'

(.)

ESA1St'O O u ~ES~A:_:_:1S:::__-_.::_3:::__5____1 ~ ii' w > D(.)"

c c ~~y~~ ~ .\\ 62 HR-J1-MW-2 , ' -~~+"-. ' "-. ~ ~ , HR-,11-MW~~ O ~~~~~~~~~ d R1111G~ ~ 2- +~ ' ' ~ :.----- ' ~

+ \ HR-J1-MW-3.__.--."Cl01'",- ' HR-G3-RWLEGEND:~' , _:_.

--- GMA 1 BOUNDARY +·'\~,~' E2SC-24-+ MONITORING WELL

ACTIVE GROUNDWA TIER64X(W) 0

AND/OR NAPL RECOVERY WELL/CAISSON

FORMER SITIE FEATURE

,A12-L3 EXTIENT OF ENGINEERED BARRIER

~ MA1-9 PROPOSED TRANSMISSIVITY TIESTING LOCATION

NS-35 + • WATER FEATURE

' ' ' r --x--x--x-- FENCE ---· N01ES:

( \. 1. MAPPING IS BASED ON AERIAL PHOTOGRAPHS AND PHOTOGRAMMETRIC MAPPING BY\ LOCKWOOD MAPPING, INC. - FLOWN IN APRIL 1990; DATA PROVIDED BY GENERAL ELECTRIC COMPANY, AND BLASLAND AND BOUCK!) ENGINEERS, P.C. CONSTRUCTION PLANS.

2. NOT ALL PHYSICAL FEATURES SHOWN .

3. SITIE BOUNDARY IS APPROXIMATE.

;, 4. ALL MONITORING WELL LOCATIONS ARE

APPROXIMATIE.

0 I 0 50' 100' GRAPHIC SCALE

GENERAL ELECTRIC COMPANY

PITISFIELD, MASSACHUSETIS

GMA 1 NAPL MONITORING PROGRAM

PROPOSED TRANSMISSIVITY

TESTING LOCATIONS

GMA-1 NEWELL STREET AREA II

FIGURE

~ARCADIS I r~=~~ultancy 2

UJ CJ

0"' UJ CJ ri UJ CJ

UJ"' a, z iij t