# Presentation: 085798

## Overview of NAPL and Groundwater Programs

- Mike Nalipinski
- EPA New England

**Notes:**
Discussion Points:
Presentation to the Housatonic River Citizens Coordinating Council (CCC) meeting held at Berkshire Community College on November 6, 2002.

## Groundwater Management Area (GMA) Map

**Notes:**
Discussion Points:
Groundwater Management Area Map
GMA boundaries chosen based on geographic location, historical use, RAA boundaries, groundwater conditions, known plumes/NAPL sources, and potential groundwater discharge location.
GMA-1 includes most of the known NAPL source areas.

## Generalized Groundwater Flow Diagram

**Notes:**
Discussion Points:
Groundwater generally flows toward the Housatonic River.
Away from the river rainwater infiltrates into the ground and the groundwater in these areas flows downward and toward the river.
Near the Housatonic River, the groundwater flows up and discharges into the river.
The top of the groundwater forms a surface in the underground soils/rocks called the groundwater table. This surface is sloped down toward the river.
Even though glacial till is dense, groundwater still flows through it, though slowly.

## Generalized Groundwater Flow Map for GMA-1 

**Notes:**
Discussion Points:
Groundwater flow direction is generally toward the Housatonic River, Silver Lake or GE recovery wells.
Local groundwater flow is variable due to differences in geology, permeability of the land surface (grass or asphalt), and recovery well pumping.
The local direction of groundwater flow can change seasonally. 
Due to spring rains and winter snow melt, the groundwater table is generally higher during the spring.

## Non-Aqueous Phase Liquids (NAPLs)

- _Definition_: Hydrocarbon Liquids (Commonly Called Oils) That Do Not Readily Mix With or Dissolve in Water (Non-Aqueous).
- Dense NAPLs (DNAPLs) Tend to Sink in Water.
- Light NAPLs (LNAPLs) Tend to Float on Water.

**Notes:**
Discussion Points:
Common NAPLs include gasoline, dry cleaning solvents and fuel oil. 
LNAPLs tend to accumulate on top of the groundwater table. If LNAPLs are present in large enough quantities, they tend to migrate down the slope of the groundwater table toward surface water bodies or pumping wells.
DNAPLs tend to accumulate on top of less permeable geologic layers such as glacial till, silt and clay. 

## NAPLs at the GE - Housatonic River Site

- Pyranol: Mixture of PCBs (Aroclors 1254 or 1260) with Trichlorobenzene. Acts as a DNAPL.
- Aroclor 1260: PCB oil. Acts as a DNAPL.
- 10C Insulating Oil: Petroleum distillate (mineral oil). Acts as an LNAPL.
- Coal Tar: Manufactured Gas Plant sludge and liquids. Acts as an LNAPL or DNAPL.

**Notes:**
Discussion Points:
GE used Pyranol as a dielectric fluid inside electrical power transformers.
10C Insulating Oil was also used by GE as a dielectric fluid inside electrical power transformers.
Coal Tar sludges and liquids were byproducts of the Manufactured Gas Plant that operated along East Street. 

## NAPL Conceptual Diagram

**Notes:**
Discussion Points:
Shows current conditions with recovery wells, sheetpile barriers, and riverbank & sediment remediation.
Contaminated groundwater is captured by recovery wells.
Sheetpile Barriers stop LNAPL from migrating to the river.
NAPL in riverbanks was remediated.
LNAPL and groundwater pumped from LNAPL recovery wells.
DNAPL (no water) pumped from DNAPL wells.

## Approximate Extent of LNAPL & DNAPL – Spring 2001

**Notes:**
Discussion Points:
NAPL Areas:
East Street Area 2 
East Street Area 1
Newell Street Area II
Lyman Street Area
1⁄2-Mile Removal – Sediments & Riverbanks
17 Automated Groundwater/NAPL Recovery Wells remove NAPL and limit contaminated groundwater flow toward the river.
7 Sheetpile Containment Barriers & 1 Slurry Wall help prevent NAPL from reaching the river.
GE operates a state of the art Groundwater Treatment Plant to remove contaminants from the groundwater.

## Approximate Extent of LNAPL at Unkamet Brook Area

**Notes:**
Discussion Points:
One additional LNAPL plume in the Unkamet Brook Area.
The LNAPL appears to be a combination of 10C Mineral Oil and No. 6 Fuel Oil.
GE conducts manual removal of LNAPL from wells in the Building 51/59 Area.

## NAPL Performance Standards

- No Discharge of NAPL to Surface Water or Sediments Around or Under Barriers.
- Eliminate NAPL from Wells Near River and Lake Banks.
- Reduce NAPL in all Wells to Minimize Potential NAPL Migration to Surface Water and Help Achieve Groundwater Standards.
- Demonstrate that NAPL Near Buildings Doesn’t Adversely Affect Indoor Air Quality.

**Notes:**
Discussion Points:
The Consent Decree established NAPL Performance Standards.
GE is required to achieve these standards.
GE must contain the NAPL – no riverbank sheens or seeps.
Where there is no barrier, GE must eliminate measurable NAPL in wells near surface water banks.
GE must prevent migration of measurable NAPL around barriers.
For NAPL areas not adjacent to surface water, GE must reduce measurable NAPL to eliminate potential NAPL migration and assist in achieving groundwater quality standards.
For NAPL detected in wells that meet GW-2 requirements (within 30 feet of an occupied building and where groundwater is less than 15 feet deep), GE must demonstrate that chemicals in the NAPL do not pose an unacceptable risk to occupants of the building via volatilization and vapor transport to the indoor air of the building.

## Sheetpile Containment Barrier & NAPL Recovery Well

**Notes:**
Discussion Points:
Lyman Street Parking Lot Area.
Riverbank restoration in progress.
Waterloo Sealed Sheetpile Containment Barrier.
NAPL & Groundwater Recovery Well and above ground pipes to transmit groundwater to treatment plant.

## Summary of GMA-1 NAPL Recovery by GE

**Notes:**
Discussion Points:
Cumulative and Yearly NAPL Recovery by GE.
Yearly NAPL recovery differences due to new pumping wells, changes in the recovery systems, seasonal variations, and pump downtime.
GE has recovered almost 1 million gallons of NAPL since the 1970s.

## Groundwater Treatment Plant and Recovery Well 64-R

**Notes:**
Discussion Points:
GE Groundwater Treatment Plant – East Street Area 2. Groundwater pumped from the Recovery Wells is piped to this plant for treatment.
NAPL Recovery Well 64-R is located next to shed with garage door.
Groundwater Recharge Pond.

## NAPL Remediation Animation, 1986 - 2000

**Notes:**
Discussion Points:
LNAPL thickness and extent from 1986 to 2000 at the largest NAPL plume at East Street Area 2.
Recovery Well locations are shown by open circles.
Sheetpile Barrier is shown in black along the river.
“V” shaped Slurry Wall is shown in red.
Selected NAPL Monitoring Well locations are shown as black dots.
The brown area shows the extent of LNAPL that is thicker than 0.8 feet (approximately 10 inches) as measured inside the Monitoring Wells.
The yellow areas shows the extent of LNAPL that is thicker than 0.1 feet (approximately 1 inch) as measured inside the Monitoring Wells.

## General Electric -  Housatonic River Project: Slide <number>

**General Electric -  Housatonic River Project: Slide **

## General Electric -  Housatonic River Project: Slide <number>

**General Electric -  Housatonic River Project: Slide **

## General Electric -  Housatonic River Project: Slide <number>

**General Electric -  Housatonic River Project: Slide **

**Notes:**
Discussion Points:
New Riverbank NAPL Recovery Wells RW-1(X) and RW-2(X) Installed.

## General Electric -  Housatonic River Project: Slide <number>

**General Electric -  Housatonic River Project: Slide **

## General Electric -  Housatonic River Project: Slide <number>

**General Electric -  Housatonic River Project: Slide **

## General Electric -  Housatonic River Project: Slide <number>

**General Electric -  Housatonic River Project: Slide **

## General Electric -  Housatonic River Project: Slide <number>

**General Electric -  Housatonic River Project: Slide **

## General Electric -  Housatonic River Project: Slide <number>

**General Electric -  Housatonic River Project: Slide **

**Notes:**
Discussion Points:
New NAPL Recovery Well RW-1(S) Installed.

## General Electric -  Housatonic River Project: Slide <number>

**General Electric -  Housatonic River Project: Slide **

**Notes:**
Discussion Points:
New East Street Area 2-South Sheetpile Containment Barrier Installed.

## General Electric -  Housatonic River Project: Slide <number>

**General Electric -  Housatonic River Project: Slide **

## Groundwater Quality Standards Massachusetts Contingency Plan (MCP) 

- MCP GW-2 Standards – Do not Exceed GW-2 Concentrations in Compliance Wells Near Buildings to Prevent Adverse Effects to Indoor Air Quality.
- MCP GW-3 Standards – Do not Exceed GW-3 Concentrations in Monitoring Wells to Protect Surface Water from Contaminated Groundwater Discharge.

**Notes:**
Discussion Points:
Massachusetts developed groundwater quality standards to evaluate the risk of harm to human health, public safety and the environment from chemicals in groundwater.
These standards and procedures for establishing risk for additional chemicals are published in the MCP (310 CMR 40.0900).

## MCP Groundwater Quality Standards - Example Table

| Analyte | GW-2 Standard (ppm) | GW-3 Standard (ppm) |
| --- | --- | --- |
| Total PCBs | Not Applicable | 0.0003 |
| Chlorobenzene | 1 | 0.5 |
| 1,2,4-Trichlorobenzene | 10 | 0.5 |
| Trichloroethene (TCE) | 0.3 | 20 |
| Naphthalene | 6 | 6 |

**Notes:**
Discussion Points:
PCBs are not volatile and do not have a GW-2 Standard.
Chemicals such as TCE and Chlorobenzene typically have a lower GW-2 Standard, since they easily volatilize into the vapor phase.

## GW-2 & GW-3 Compliance Wells

**Notes:**
Discussion Points:
GW-2 Wells are located near occupied buildings.
GW-3 Wells are located near Surface Water bodies – at groundwater discharge points. 
GW-3 Wells are located next to the Housatonic River, Silver Lake and Unkamet Brook.

## Groundwater Monitoring Well Installation & Sampling

**Notes:**
Discussion Points:
The groundwater and NAPL recovery and monitoring activities are not as noticeable at the site when compared to the riverbank and sediment removal actions.
Most of the activities are of short duration and typically only require a van and two field scientists. Even the well drilling and installations typically only take one day to complete.
The photo on the left shows a GE subcontractor installing a GW-3 groundwater monitoring well on the Housatonic riverbank between the Newell and Lyman Street Bridges.
The photo on the left shows a GE subcontractor sampling one of the GMA-1 monitoring wells and measuring the depth to water in the well.

## Groundwater Monitoring Program

- _Baseline Groundwater Monitoring Program_
- Designed to Establish Current Conditions
- Quarterly Water Level Monitoring
- Semi-annual Groundwater Quality Sampling for Two Years
- _Long-Term Groundwater Monitoring Program_
- Designed to Verify Attainment of Standards Over Time
- Program Specifics to be Determined After Baseline Program is Completed
- Monitoring/Sampling to be Conducted at Intervals of No More Than 2 Years.

**Notes:**
Discussion Points:
As of November 2002, GE is still conducting the Baseline Monitoring Program.
GMA-1 was the first GMA to be sampled and its Baseline Monitoring Program should be completed first. The other GMAs will be completed after GMA-1.
GE shall propose a Long-Term Groundwater Monitoring Program for each GMA, subject to EPA review and approval,  to include:
Wells to be sampled
Frequency of sampling
Chemical analyses to be conducted

## Groundwater Sampling/Testing Team

**Notes:**
Discussion Points:
GE field crew conducting hydraulic testing of a monitoring well in East Street Area 2-North next to Building 17.
Typical field crew and truck.

## GMA-1 & GMA-5 Compliance Wells

**Notes:**
Discussion Points:
Distribution of GMA-1 and GMA-5 groundwater monitoring wells.
GMA-5 covers the Oxbow A & C area.
GMA-1 covers the remaining areas visible on the map. 
GW-2 wells are typically located next to occupied buildings.
GW-3 wells are located:
Next to the river and lake.
At the edge of GE’s property.
Near known contaminant source areas.
Some wells serve two purposes – GW-2 and GW-3 monitoring.

## GMA-2 & GMA-4 Compliance Wells

**Notes:**
Discussion Points:
Distribution of GMA-2 and GMA-4 groundwater monitoring wells.
GMA-2 covers the Oxbow J & K area.
GMA-4 covers the On-Plant Consolidation Areas (Hill 78 and Building 71), the Power Generating Plant and the General Dynamics area.

## GMA-3 Compliance Wells

**Notes:**
Discussion Points:
GMA-3 covers the Unkamet Brook Area.
GE also samples Natural Attenuation Wells at this GMA.
The Natural Attenuation sampling is designed to monitor the natural breakdown and dilution of contaminants in groundwater over time.

## Overview of NAPL and Groundwater Programs