Updated November 20, 2024
GENERAL TOPICS
Q. What was a Manufactured Gas Plant (MGP)?
A. Prior to the widespread availability of natural gas, gas was “manufactured” through a process of heating coal in specialized ovens. These gas manufacturing facilities, called Manufactured Gas Plants (MGP), were common in many urban areas of the United States during the late nineteenth and early twentieth centuries.
Manufactured gas was used for residential and street lighting and cooking. The manufactured gas process produced by-products, such as coal tar and other chemicals that were also used in the chemical, dye and pharmaceutical industries.
Q. Where is the site located?
A. The former West Station Gas Works was built in 1858 and was located near what is currently the intersection of New Hampshire Avenue NW and Virginia Avenue NW, in the Foggy Bottom neighborhood. A majority of the Site was located within the area generally bound by Virginia Avenue NW to the northeast, New Hampshire Avenue NW to the southeast, F Street NW to the south, and the Potomac River to the west.
Q. When did the former plant operate?
A. The former West Station MGP operated from 1858 through 1946, when it was decommissioned. In accordance with the practice of the day, the former plant’s aboveground structures were demolished to ground surface between the late 1940s and late 1950s, with soil placed in gas holder foundations. Efforts were made at the time to remove the plant’s piping, tanks, and other structures. However, some remnants and associated byproducts from MGP operations may remain buried below ground as was common with MGP decommissioning at the time.
Q. Who is conducting the investigation of the site?
A. Washington Gas and their environmental consultant GEI Consulting, Inc. (GEI) are conducting the investigation.
Q. Who is supervising the work?
A. District of Columbia Department of Energy and Environment (DOEE).
Q. What are the materials of concern?
A. Compounds considered to be of potential concern that are a focus of the Washington Gas investigation include polycyclic aromatic hydrocarbons (or PAHs) and benzene, toluene, ethylbenzene, xylene(s), and naphthalene (BTEXN).
Q. What work was previously performed?
A. In 1998, Washington Gas performed an indoor air quality assessment in each of the six buildings in the Watergate Complex, they include:
- 2700 Virginia Avenue NW
- 2600 Virginia Avenue NW
- 2650 Virginia Avenue NW
- 2500-2560 Virginia Avenue NW
- 600 New Hampshire Avenue NW
- 700 New Hampshire Avenue NW
This testing did not identify MGP-related chemicals in the air above detection limits that were achievable at the time.
In addition, Washington Gas installed a depressurization system in the Watergate East boiler room of 2500-2560 Virginia Avenue NW in 1978 to relieve hydrostatic pressure. Groundwater from the depressurization system is filtered prior to discharge into the sanitary sewer system under a permit. This system has been in operation for more than 30 years. Vicinity Energy assumed operation of the system in 2018.
Q. What are the risks?
A. While the constituents that are the focus of this investigation can pose a risk if swallowed, this is unlikely. Groundwater, where MGP constituents may be found, is not used for drinking purposes, nor is there typically ingestion of soil below the ground surface. In addition, the majority of the Site is covered by a mix of buildings, roadways, some vegetation, and concrete. Collectively these features reduce the potential for direct contact. MGP-related chemicals were not identified above detection limits during indoor air quality assessments performed in 1998 at each of the six buildings in the Watergate Complex. The planned indoor air assessment will provide updated indoor air quality information for comparison with currently applicable indoor air risk levels.
Q. Who do I contact if I have a question or concern?
A. Call the Project Information Line at (202) 964-5140. Leave a voicemail and one of Washington Gas’ community liaisons will return your call as soon as possible. Or email us at comments@weststationproject.com.
Q. What is the focus of current activities?
A. In accordance with a directive from the District of Columbia Department of Energy and Environment (DOEE), Washington Gas submitted a draft Site Investigation Work Plan for regulatory review in January 2024 to allow Washington Gas to take a comprehensive approach to this project. In April 2024, DOEE gave approval to begin implementation of the Site Investigation. The Work Plan includes investigation details for soil, groundwater, surface water, sediment, and indoor air quality. Washington Gas has engaged GEI Consulting, Inc. (GEI), a company with extensive MGP-related experience to develop and assist Washington Gas with implementing the investigation under DOEE oversight.
INDOOR AIR SAMPLING
In spring 2024, GEI developed building-specific work plans to perform indoor air quality assessments for the buildings located within the footprint of the former MGP site: the six buildings of the Watergate Complex (2700 Virginia Ave. NW, 2600 Virginia Ave. NW, 2650 Virginia Ave. NW, 2500-2560 Virginia Ave. NW, 600 New Hampshire Ave. NW, and 700 New Hampshire Ave. NW) and Potomac Plaza Apartments (2475 Virginia Ave. NW), Potomac Plaza Terraces (730 24th St. NW), and Western Presbyterian Church (2401 Virginia Ave. NW).
DOEE reviewed the work plans and approved Washington Gas to perform two rounds of indoor air sampling – one round in the cooling season and one round in the heating season. One round of sampling during each season is required because air conditioning and heating systems influence how air flows within a building.
Q. What is WG testing for?
A. We will be looking for those constituents typically associated with former MGP operations, which include benzene, naphthalene, and other organic compounds associated with residual coal tar from the MGP process. The sample data will be compared to regulatory indoor air screening levels to verify whether constituents are below currently applicable risk thresholds.
Q. Where will indoor air sampling be conducted?
A. Indoor air samples will be collected from the basement(s) and/or lowest levels of buildings located within the footprint of the former MGP site. These include the six buildings of the Watergate Complex: (2700 Virginia Avenue NW, 2600 Virginia Avenue NW, 2650 Virginia Avenue NW, 2500- 2560 Virginia Avenue NW, 600 New Hampshire Avenue NW, 700 New Hampshire Avenue NW), Potomac Plaza Apartments (2475 Virginia Avenue NW), Potomac Plaza Terraces (730 24th Street NW), and Western Presbyterian Church (2401 Virginia Avenue NW). Owners of all buildings where indoor air sampling will take place have been contacted. The work will be performed in coordination with the individual property owners through their management representatives.
Q. When will the indoor air sampling be conducted?
A. Two rounds of sampling are required. The first round was completed by mid-September 2024 in coordination with the individual property owners through their management representatives. Samples were collected from within the basement(s) and/or lowest levels of each building. Ambient air samples were collected from outdoor locations.
The second round of sampling is planned for the first quarter of 2025. Results from both rounds of sampling are required before an assessment of indoor air conditions at each building can be completed.
Q. How will indoor air sampling be conducted?
A. The assessment is a multi-step process. The first step is to complete a survey of the area where the air testing will be performed. A GEI representative will identify existing potential background sources of chemicals present in indoor air (i.e., sources unrelated to historic MGP material such as candles, cleaning supplies, smoking, petroleum products, and vehicle exhaust). Anything that can be removed will be relocated or stored elsewhere temporarily prior to and during sampling.
The second step is to collect both indoor air and background samples for each building over a 48-hour period by placing small air canisters and pumps in the lowest levels of each building. One type of canister has a negative pressure and a regulator to slowly draw air in over the period of the testing time. It is a silent process. The second type is a small pump that pushes the air over a sampling “rod” that captures the particles. There is a low hum associated with its operation. The sample collection is performed over two consecutive 24-hour periods. All samples will then be sent to a licensed laboratory for analysis and the data will be reported to DOEE.
A follow-up sampling event may be conducted as a third step, depending on the results of the initial sampling. This would be done to confirm the results and assess the source of the data.
SOIL AND GROUNDWATER SAMPLING
In late August, GEI began soil sampling along the Potomac River in an area where our investigation overlaps with the DC Water Potomac River Tunnel project near Rock Creek Trail, west of the Watergate Complex (near CSO 22). This work was completed in October 2024.
Soil sampling will continue through January 2025 on or near each of the properties located within the former MGP footprint and near the Thompson Boat Center.
A fenced-in storage area for construction equipment and materials is established on the grassy area along the northern side of the Rock Creek Park Thompson Boat Center parking lot.
Q. Where is soil sampling being performed?
A. Work began along the Potomac River in an area where our investigation overlaps with the DC Water Potomac River Tunnel project near Rock Creek Trail, west of the Watergate Complex (near CSO 22). Soil sampling is continuing through January 2025 on or near each of the properties located within the former MGP footprint and near the Thompson Boat Center.
Q. How will groundwater sampling be conducted?
A. Groundwater will be investigated through installation and sampling of a network of groundwater monitoring wells.
GEI is working with DOEE to finalize all sampling locations based upon the presence of utilities and subsurface conditions. GEI is conducting this work in coordination with building managers and DC police, if needed, with pedestrian and vehicle safety in mind.
SURFACE WATER AND SEDIMENT SAMPLING
In spring 2025, sampling of Potomac River surface water and sediments is planned. This work will be coordinated with Thompson Boat Center, NPS, USACE, and DOEE.