Metropolitan Transportation Authority Long Island Railroad Long Island City Passenger Yard
Posted on October 15, 2009
Client: Metropolitan Transportation Authority Long Island Railroad
Location: Long Island City
Project Type: Remedial Investigation
Project Period: August 2005 - October 2009
Project Cost: $149,000
The firm was retained by the Metropolitan Transportation Authority’s (MTA’s) Long Island Railroad (LIRR) to implement a Remedial Investigation of the Long Island City Passenger Yard (the Yard), located in Long Island City, Queens County, New York. The project was initiated by the LIRR pursuant to a New York State Department of Environmental Conservation (NYSDEC) Administrative Consent Order designed to address environmental impacts to soil and groundwater associated with historical releases of petroleum (diesel fuel) at the Yard.
The objectives of the Remedial Investigation project included the following:
- Identify the nature and extent of soil and groundwater contamination associated with historical releases of petroleum that have occurred at the Yard;
- Determine whether off-site migration of light non-aqueous phase liquid (LNAPL) and dissolved-phase contamination has occurred; and
- Identify areas that may warrant further investigation and/or remediation.
Background and Site History
The Long Island City Passenger Yard is located in a highly industrialized area of Long Island City, New York, south of Borden Avenue, between Second Street and 11th Avenue. The Yard consists of an approximately 7-acre track area, several temporary office and equipment storage buildings and a concrete passenger platform. A New York City Transit Authority (NYCTA) subway line and four Amtrak rail tunnels are located beneath the Yard. A Triborough Bridge and Tunnel Authority (TBTA) property used for storage of road salt borders the northwestern corner of the Yard and an oil storage and distribution center is located south of the eastern portion of the Yard. South of the western portion of the Yard is Fink Baking Corporation. The Queens Midtown Tunnel is located to the north of the Yard.
Historically, the Yard has been used for the fueling, maintenance and storage of diesel-powered trains. However, maintenance and fueling activities have been significantly scaled back in recent years with the arrival of an updated diesel-powered fleet. Currently, diesel trains arrive from eastern Long Island after the morning (westbound) peak period and are refueled for the afternoon (eastbound) peak period. Presently, passenger coach interiors are cleaned and minor repairs are made to railcars at the yard. As part of current locomotive fueling operations, diesel fuel is conveyed from a 10,000-gallon aboveground storage tank (AST) located on the eastern end of the Yard to the western portion of the Yard via underground piping. The current fueling system includes a leak detection system and “catch pans” that are located beneath the track where the locomotives are being fueled. The catch pans are designed to capture any potential spillage that may occur during fueling activities. In the event of a spill, the catch pans are designed to contain the fuel and convey it to an oil-water separator located in the northeastern portion of the Yard, preventing any release to the soil.
As a result of historical spills, on-site soil and groundwater has been impacted by diesel fuel. Between December 1993 and December 1995 three investigation phases were completed by the LIRR at the Yard. The investigations identified the most significant soil and groundwater contamination as being present in the western third of the Yard. In addition, LNAPL was consistently detected in several monitoring wells located in the western portion of the Yard.
In 1996, the LIRR installed an LNAPL-recovery system in five monitoring/recovery wells in order to remediate this contamination. According to LIRR personnel, the LNAPL recovery system was shut down temporarily in December 1997 and was then reactivated in 1998. The system continued to operate until July 2002, at which time the system was permanently shut down.
From 2002 to 2008, the LIRR undertook a major reconstruction and improvement project at the Yard. As part of the reconstruction and improvement project, one abandoned 1,450-gallon waste oil underground storage tank (UST) and one 20,000-gallon diesel fuel UST were removed from the Yard. In addition, approximately 31,666 cubic yards or approximately 47,500 tons of petroleum-contaminated soil was excavated for off-site disposal from the northern, western and central portions of the Yard.
Remedial Investigation Scope of Work
In August 2005, the LIRR retained D&B Engineers and Architects, P.C. to undertake a remedial investigation (RI) of the petroleum contamination at the Yard remaining after completing the Yard reconstruction discussed above. D&B’s investigation was completed in the southern third of the Yard focused primarily in the southwestern corner. D&B undertook several preliminary field activities, including a site reconnaissance survey and the sampling of the existing monitoring well network, in order to provide a better understanding of existing site conditions and to develop the scope of work.
Through our cooperative effort with the LIRR and our extensive experience in the characterization of petroleum-impacted sites, the September 2006 RI Work Plan was approved by the NYSDEC with only minor comments and the RI was underway by December 2006. Since much of the fieldwork had to be completed within an active rail facility, D&B worked closely with the LIRR yard managers to ensure that their normal activities were not disrupted during the execution of this work and the work was performed in accordance with all LIRR safety regulations. The RI scope of work was completed on schedule and under budget and included the following elements:
- Underground Utility Clearance – Prior to conducting any intrusive activities a utility clearance was conducted including obtaining utility markouts through the Code 753 process. In addition, the upper five feet, at a minimum, at each intrusive sampling location was cleared using hand tools in order to ensure the absence of underground utilities.
- Piezometer Installation and Subsurface Soil Sampling – Ten piezometers were installed along the northern, southern and western boundaries of the Yard utilizing a track-mounted direct push rig in order to evaluate groundwater flow and quality at the Yard. In addition, a total of 12 subsurface soil samples were collected during the piezometer installation process to evaluate subsurface soil conditions.
- Groundwater Probe Sampling – In an effort to delineate the southern limit of LNAPL and, with the approval of the LIRR and the NYSDEC, two off-site groundwater probes were installed in the vicinity of the southwest corner of the yard using a track-mounted direct push rig.
- Monitoring Well Installation and Subsurface Soil Sampling – Four monitoring wells were installed in the vicinity of the southwest portion of the Yard using hollow-stem auger drilling methods to further assess groundwater quality. The well locations were chosen in consultation with the NYSDEC and were based on the derived groundwater flow direction, LNAPL gauging results and existing groundwater sample results. In addition, a total of seven subsurface soil samples were collected during the well installation process to evaluate the subsurface soil conditions.
- Surveying – The elevation of all newly installed piezometers and monitoring wells were surveyed to an accuracy of 0.01 foot using the Queens County datum. In addition, six of the intact existing wells were re-surveyed. Two elevation measurements were taken at each location, the ground surface elevation and the elevation of the top of the well casing.
- Piezometer and Monitoring Well Sampling – Subsequent to development, three rounds of groundwater samples were collected from all accessible piezometers and monitoring wells. In addition, groundwater samples were only collected from piezometers and monitoring wells that did not contain free-phase LNAPL at the time of sampling.
- Well Gauging – Well gauging was completed during each of the three rounds of groundwater sampling and one additional round completed in June 2008. This task included measurements of depth to LNAPL and thickness of LNAPL, if any, and depth to groundwater. The information obtained during the well gauging process was used to generate groundwater elevation contour maps and subsequently determine groundwater flow directions.
- Tidal Survey – A tidal study was conducted to determine whether the proximity of the Yard to the East River and Newtown Creek results in any tidal influence to groundwater at the Yard. The study was conducted utilizing three of the installed on-site piezometers over an approximate 24 hour period in January 2007. For the study, MiniTROLL pressure transducer/data logger systems were installed in targeted wells in order to record the hydraulic head pressure within the well at pre-programmed intervals and convert the readings into height of the water column above the transducer probe. All collected elevation head data were later downloaded in digital format and used to generate graphs depicting groundwater elevations in the selected piezometers over the study period in order to identify any sinusoidal fluctuations in the water table that could be attributed to tidal influence.
Key Findings of the Remedial Investigation
The generated field and chemical data was evaluated by D&B’s experienced technical staff in order to characterize the hydrogeology of the Yard and surrounding area, and to assess the nature and extent of petroleum contamination in soil and groundwater.
Bedrock underlying the Yard consists of a granodiorite gneiss and varies from 18 feet below grade in the western portion of the Yard to 30 feet below grade in the eastern portion of the Yard. Site soil consists of highly variable fill material present from the ground surface up to five feet below grade. Below the fill is a fine sand, silt and organic-rich clay typical of marsh deposits. Based on the pre-development setting of the westernmost end of Long Island, it is assumed that the marsh deposits constitute native sediments that were filled during the development of this area. Given the filled nature of this portion of Queens and the construction of numerous subsurface tunnels in the area, the natural stratigraphy of the Yard and surrounding properties has been substantially altered.
Groundwater was encountered at depths ranging from approximately 3 to 7 feet below grade at the Yard and flows generally toward the northwest in the western portion of the Yard and toward the northeast in the eastern portion of the Yard. A local high point in the water table appears to be located in the south central portion of the Yard. These patterns of groundwater flow are generally consistent with those from previous investigations. However, the installation of a number of wells in the southwestern portion of the Yard suggests a southerly flow component in this area. As described below, this area also contains a localized area of free-phase LNAPL.
While groundwater flow would be towards nearby surface water such as the East River to the west of the Yard under natural undeveloped conditions, groundwater flow patterns in this highly urbanized environment are complicated by a number of factors, including:
- The heterogeneous nature of the fill material;
- The presence of former tidal creeks and channels that may serve as “preferred flow paths”;
- The presence of storm sewers and utility conduits that may serve as “drains” for groundwater;
- The presence of numerous subsurface tunnels and utilities throughout the area; and
- “Dewatering” of the nearby tunnels and/or construction projects that may be occurring in the immediate vicinity of the Yard.
Furthermore, the presence of free-phase LNAPL such as in the southwestern portion of the Yard will also depress the water table to some degree which may further complicate the assessment of groundwater flow.
Results of the tidal survey indicated that the tidal fluctuation of the East River was between 4 and 5 feet during the tidal study period, whereas groundwater elevations in on-site monitoring wells varied by less than 0.03 feet, indicating little, if any tidal influence.
Extent of Petroleum Contamination
Four rounds of well gauging were conducted as part of the Remedial Investigation. Measurable free-phase LNAPL was observed ranging in thickness from 0.08-foot to 2.74 feet. Utilizing data from 12 monitoring wells and piezometers in the southwestern portion of the Yard, the extent of the free-phase LNAPL has been defined as encompassing an area of roughly 360 feet long in an east-west direction and roughly 50 to 100 feet wide in a north-south direction. The monitoring wells installed off-site to the south indicate little, if any, off-site migration of the free-phase LNAPL.
This area also contained petroleum impacted soil exhibiting black staining and petroleum like odors up to approximately 8 feet below grade. Soil samples selected for analysis were found to contain elevated volatile organic compounds (VOCs), consisting predominantly of benzene, toluene, ethylbenzene and xylene (BTEX) and benzene-related compounds, with a maximum total VOC concentration of 243.0 ppm. In addition, several elevated semivolatile organic compounds (SVOCs), consisting predominantly of polycyclic aromatic hydrocarbons (PAHs), were detected in soil, with a maximum total SVOC concentration of 159.8 ppm. However, the extent of this petroleum contamination was not fully defined.
Groundwater was found to contain elevated VOCs, consisting predominantly of BTEX, with a maximum total VOC concentration of 189.2 ug/l. In addition, several SVOCs were detected, consisting predominantly of PAHs, with a maximum total SVOC concentration of 43.6 ug/l.
In summary, the most significant petroleum impacts were identified in the southwest portion of the Yard and are consistent with the area defined as containing free-phase LNAPL. While some migration of dissolved phase petroleum contamination has occurred off-site to the south of this area, off-site migration of free-phase LNAPL appears to be very limited.
Based on the review of the generated data as part of this RI, the NYSDEC directed the LIRR to install four replacement monitoring wells in the central portion of the Yard. While this portion of the Yard was excavated as part of the Yard reconstruction, the NYSDEC was interested in monitoring any residual petroleum in this area. In addition, a fifth monitoring well was recommended for installation in the northwestern portion of the Yard where petroleum was formerly stored at the Yard.
Long-term groundwater monitoring was recommended to be continued in order to detect any changes in LNAPL thickness and extent, and to ascertain the effectiveness of the LIRR’s completed excavation of the northern two-thirds of the Yard in reducing LNAPL levels. Groundwater monitoring was recommended to include monthly monitoring of all accessible piezometers and monitoring wells for the presence of free-phase LNAPL. In addition, quarterly groundwater sampling was recommended in order to assess any changes in the dissolved-phase groundwater contamination.
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