14-1 June 2021

Chapter 14: Soils and Geology

14.1 INTRODUCTION 

The types of soils and geologic conditions, as well as the potential for seismic activity at a project 

site, need to be accounted for as part of the design for a proposed action. Potential construction 

considerations with respect to geologic structure and faults, seismicity, slope stability, and unique 

geologic features, are identified based on available soils and geologic data. This information 

informs the engineering design for structural foundations, and helps with estimates of the amount 

of materials to be excavated, and identification of any dewatering needs during construction. This 

chapter describes the analysis FRA conducted of the potential effects of the No Action Alternative 

and the Preferred Alternative on soils and geologic conditions, as well as the potential for seismic 

activity in the area, which the Project Sponsor would need to account for as part of the design of 

the Preferred Alternative. These analyses also describe potential impacts of the Preferred 

Alternative following construction. FRA has evaluated potential impacts with respect to geologic 

structure and faults, seismicity, slope stability, and unique geologic features, based on available 

soils and geologic data.

14.2 REGULATORY CONTEXT

There are no relevant Federal or state regulations or executive orders for evaluating impacts to 

geologic resources or soils. However, a geotechnical evaluation of geologic resources, including 

soil borings and collections to determine appropriate foundations for the Preferred Alternative is 

required. The design and construction of the Preferred Alternative would be in accordance with 

the following guidance document and local codes and regulations: 

• New York City Building Code, 2014 edition

• NYCDOB Regulations

• ASCE 7–10, 2010 edition

14.3 ANALYSIS METHODOLOGY

The Study Area for this resource category is the Project Site. FRA analyzed existing reference 

information about the soils and geology at the Project Site to identify type of soil/geology present, 

analyzed support needed for the engineering design for the Tunnel Encasement and Platform 

structure foundations, estimated the amount of materials to be excavated from the site, and 

identified any dewatering needs during construction of the Preferred Alternative. Please see 

Analysis Methodology in Chapter 11 of Appendix B, for a complete description of the 

methodology used for the analysis of this resource category.
June 2021 14-2 

14.4 AFFECTED ENVIRONMENT

14.4.1 GEOLOGY

The Study Area is reclaimed land, formerly part of the Hudson River, which was purposefully filled

to expand Manhattan Island’s shoreline within the last 200 years. Urban fill is typically reworked 

sandy and granular geologic materials, generally containing various inclusions such as cinders, 

construction debris, or other refuse. The natural soils under the fill consist of alluvial sediment. 

The sediment of this area along the Hudson River is primarily soft clays and silts with varying 

amounts of fine sand. With depth, this alluvial sediment transitions to denser glacial soils, typically 

a mixture of clay and sand with occasional areas of gravel, cobbles and boulders. The bedrock at 

the site is characterized by metamorphic rock ranging from about elevation (el.) +20 feet beneath 

Eleventh Avenue to about el. -110 feet beneath Twelfth Avenue, with elevations being referenced 

to the National Geodetic Vertical Datum of 1929 (NGVD29) datum. See Figure 14-1 for an excerpt 

of USGS Bedrock mapping, which indicates the bedrock contours and the demarcation of the 

man-made fill area. See Appendix J1, “Geotechnical Report-Platform,” and Appendix J2, 

“Geotechnical Report-Terra Firma,” for more detailed information regarding the characteristics of 

the geology of the Project Site.

14.4.2 SEISMIC ACTIVITY AND FAULTS 

The Study Area is located on the western side of Manhattan Island. Based on Figure 14-1, the

nearest fault line is about 1.5 miles to the east, with another fault line about 2 miles to the south. 

These represent older fault lines that are not tectonically active (such as those on the western 

coast of the United States, where seismic activity is more prevalent) (see Appendix J3, “SiteSpecific Seismic Study.”) 

Available information from USGS does indicate that there is probabilistic chance that a future 

seismic event could be experienced in the Study Area. The USGS data is based on seismic activity 

around the United States, and takes into consideration the frequency and magnitude of such 

activity—those activities which usually result in an earthquake. While it is reasonable to expect 

that a future earthquake having a magnitude between 5.0 and 6.0 could occur, the data from 

USGS does not indicate when such a seismic event could occur, and if the actual magnitude would 

be higher or lower than the range currently expected. 

14.4.3 SOIL 

The Study Area comprises UrA, urban land, reclaimed substratum.

1

1 https://websoilsurvey.sc.egov.usda.gov/

Urban land soils are areas 

covered by impervious materials such as asphalt. The soils that comprise these urban lands were 

material that were dumped in order to advance the shore line westwards into the Hudson. As 

shown on Figure 14-2, the Study Area is located outboard of the original western shoreline of 

Manhattan (which is assumed to date back to the time of colonization of Manhattan island in the 

1600s). The soils are materials which may have been excavated from other nearby areas, but may 

also include debris as the shoreline was pushed westward into the Hudson River. 

14.4.4 GROUNDWATER AND AQUIFERS

The groundwater in the Study Area is not part of an aquifer used for public potable water. New 

York City’s system of upstate reservoirs provides drinking water to the city. Groundwater is 

discussed in Chapter 12, “Contaminated Materials.” 
10.30.20

0 0.25 MILES 

Project Site (Western Rail Yard) 

Bedrock Map 

WESTERN RAIL YARD INFRASTRUCTURE PROJECT Figure 14-1 
Original

Shoreline

WESTERN RAIL YARD INFRASTRUCTURE PROJECT

1865 Viele Map

Figure 14-2

0 1,000 FEET

3.10.21

Project Site (Western Rail Yard) A
Chapter 14: Soils and Geology

14-3 June 2021

14.5 ENVIRONMENTAL CONSEQUENCES

14.5.1 NO ACTION ALTERNATIVE 

No impacts affecting the soils and geology would occur under the No Action Alternative since no 

excavation or foundation construction would occur. As such, the Project Site would remain in use 

as an open rail yard, and the current LIRR operational facilities would remain on the terra firma 

portion of the Project Site.

14.5.2 OPERATIONAL IMPACTS OF THE PREFERRED ALTERNATIVE

The Preferred Alternative would require the support of excavation structures and foundation 

structures intended to function over the 100-year design life. The Project Sponsor would design 

these structures to transfer load of the Overbuild to the underlying bedrock. 

The groundwater level is currently below the elevation of the existing rail yard. Since there would 

be no intent to change the elevation of the rail yard as part of the Preferred Alternative, FRA has 

determined that no impact to the groundwater would result from the Preferred Alternative. Impacts 

to groundwater are discussed in Chapter 12. 

14.5.2.1 PLATFORM

The design of the 9.8-acre Platform spanning the Western Rail Yard would include deep 

foundations and a concrete slab to cover the active rail yard below, and reinforced building 

foundations to support the planned Overbuild. The Project Sponsor would drill approximately 400

caissons (i.e., watertight columns) into bedrock through the water table and soil to the rock that is 

as deep as 120 feet below the surface in certain locations. The design for the Platform’s support 

columns would thread them between the existing railroad tracks and associated infrastructure in 

the Western Rail Yard. Bedrock would support the caissons.

The caissons, located between the set of tracks, would form a grid pattern, with a greater number 

of caissons in the areas where the buildings of the Overbuild would be located above. Depending 

on the vertical and horizontal loads on the caissons, the distance between caissons would be 

between about 10 and 80 feet, and the diameter of the caissons would range from about 24 inches 

to 60 inches. Once constructed, the Platform would not have an impact on the underlying soils 

and bedrock since construction of the caissons would remove materials and replace them with 

concrete. 

14.5.2.2 TUNNEL ENCASEMENT

The Tunnel Encasement in the Western Rail Yard would extend diagonally across the Project Site, 

and would be between approximately 50 and 65 feet wide and between approximately 27 and 38 

feet high. See Chapter 3, “Alternatives,” for a more detailed description of the Tunnel Encasement. 

Per the Project Sponsor’s design, secant pile walls would compose the Tunnel Encasement. 

Secant piles consist of a series of interlocking concrete cylinders that form support for the structure 

above and a waterproof basement wall. 

Once in place, the casing would be adequate to support the adjacent soils and any structures 

placed above it.

The Tunnel Encasement would not have an impact on the underlying soils and bedrock, since the 

encasement would be fixed in place and designed to withstand the lateral loads of soil and 

bedrock, and would not result in any further changes to the soils or bedrock in the area. 
June 2021 14-4 

14.5.3 CONSTRUCTION IMPACTS OF THE PREFERRED 

ALTERNATIVE

14.5.3.1 EXCAVATION AT TUNNEL ENCASEMENT

As stated previously, the Tunnel Encasement would require secant piles. Installing secant piles 

involves the construction of guide walls, which provide an accurate alignment for the drilling auger. 

A drilling rig then advances an initial series of cylindrical holes to the desired depth (the primary 

piles), spacing them slightly less than one pile diameter apart. A concrete pump is connected to 

the drilling apparatus, and fills the holes with slow-curing, or soft, concrete to form piles. The rig 

then drills a second series of holes for the secondary piles, which intersect each primary piles at 

two locations (the secant). The drilling equipment and concrete pump then fill the secondary piles 

with concrete, while a crane lowers the steel reinforcement into the secondary pile. After 

completion (and curing) of all concrete secant piles, hydraulic excavators can excavate the tunnel 

cavity to the desired depth or until bedrock is encountered. 

Excavation for the proposed Tunnel Encasement would vary in depth from about 60 feet below 

existing ground surface near Eleventh Avenue to about 70 feet below existing ground surface at 

its maximum depth near Twelfth Avenue. Therefore, rock blasting would be necessary to excavate 

about 25,000 cubic yards of bedrock to create a trench for construction of the concrete casing.2

2 Amtrak and FRA. November 2014. Finding of No Significant Impact, Supplemental Environmental 

Assessment for Construction of a Concrete Casing Extension in the Hudson Yards, New York, New York.

Excavation would involve controlled rock blasting techniques, with special techniques such as 

channel drilling and rock splitting planned in some areas to reduce vibration on nearby facilities, 

buildings, tracks, and railroad systems and operations. 

Bedrock excavation within the Tunnel Encasement would fragment the bedrock a combination of 

controlled blasting, chemical fracturing, or hoe ramming, removing the fractured rock by hydraulic 

excavator. Controlled blasting dislodges rock from the underlying parent material by the detonation 

of explosive charges placed in holes drilled into the bedrock under a prescribed regime that 

considers geologic factors and the number, depth, and spacing of explosive charges to maximize 

the fracturing effect of the blast while minimizing the strength of the charge and resultant vibration. 

The excavation of any dislodged rock would then occur, exposing the undisturbed bedrock. The 

Project Sponsor would repeat this process until it achieves the desired depth. See Section 14.6.3 

in this chapter for a discussion of potential vibration impacts from construction activities and the 

methodology and procedures for measuring and minimizing vibration. Construction of the Tunnel 

Encasement would permanently remove about 25,000 cubic yards of bedrock,3

3 Amtrak and FRA. November 2014. Finding of No Significant Impact, Supplemental Environmental 

Assessment for Construction of a Concrete Casing Extension in the Hudson Yards, New York, New York.

and there would 

be no adverse environmental impacts. 

The construction of the Tunnel Encasement would not have an impact on the underlying soils and 

bedrock, since the drilling and installation of secant piles is implemented to remove soil and 

bedrock materials in a contained and controlled manner. The secant piles are designed to 

withstand the lateral loads of soil and bedrock, to provide a stable excavation can be created for 

the Tunnel Encasement. 

The Project Sponsor would truck excavated rock material to a crushing and recycling facility, 

beneficially reuse it off-site, or haul it to a permitted disposal facility. 
Chapter 14: Soils and Geology

14-5 June 2021

The Project Sponsor would handle excavated soil and bedrock either by stockpiling it on-site or 

loading it directly onto trucks and hauled off-site for reuse or disposal. The Project Sponsor would 

remove, transport, and dispose of the soil/rock at licensed disposal facilities in accordance with 

regulatory guidance and action levels established in federal, state, and municipal standards. The 

Project Sponsor would perform the excavation and material removals in coordination with NYCT, 

LIRR, the MTA, and Amtrak to limit interference with rail operations during removals. For bedrock 

removal, the Project Sponsor’s contractor would obtain and adhere to the excavation, rock splitting 

and blasting permit from the NYCDOB and/or the New York City Fire Department (FDNY). The 

Project Sponsor would monitor vibrations during construction and develop action levels to evaluate 

the potential impacts of the contractor’s means and methods for removal of rock and soil on 

adjacent facilities.

14.5.3.2 DEWATERING AT TUNNEL ENCASEMENT

A support of excavation system that utilizes secant piles typically requires minimal dewatering 

once the initial dewater of the excavation takes place, compared to support of excavation systems 

that traditionally use solider piles and lagging panels. Note that the secant piles would be used to 

support excavations in soil materials. As excavation to the bottom of the Tunnel Encasement 

continues into bedrock, the existing groundwater—which may flow through joints, cracks, or 

fractures in the bedrock mass that is not treated with secant piles—would require pumping and 

treatment in accordance with the dewatering plan.

14.5.3.3 EXCAVATION FOR CASSIONS

To install caissons, the Project Sponsor would drill 24- to 72-inch diameter holes vertically into the 

ground. As the drill advances holes, a metal casing would be advanced with the drill head to keep 

the drill hole open. When the drilling activity reaches bedrock, a drill head designed for drilling rock 

would replace the drill head designed for soil. The new drill head (for bedrock) would continue 

advancing the hole between about 8 and 40 feet into the bedrock, creating a rock socket; the exact 

depth of which would be dependent on the diameter and load-carrying capacity of the caisson. 

The drilling head and drilling equipment remove the soil and bedrock debris as the hole is being 

drilled. It is estimated that approximately 16,000 cubic yards of soil and 5,000 cubic yards of rock 

would be excavated as a result of caisson installation. Once the drill head has reached the bottom 

of the rock socket, a concrete pump would be connected to the drill rig, and concrete would be

pumped into the cased hole and rock socket, as the steel beam reinforcement is lowered and 

centered within the casing and rock socket.

The metal caisson for each pile would extend approximately two feet above the surface of the 

yard. Bolts embedded in the concrete would extend above the top of the pile in order to attach 

base plates to the pile. 

Construction of a caisson would require a minimum of four major pieces of equipment, including 

a foundation-drilling rig, cranes to install casing and reinforcement, a front-end loader to load soil 

and rock spoils onto trucks, a concrete pumper, and cranes to install base plates and structural 

steel atop the caisson foundation. Multiple caisson installation operations would likely occur 

simultaneously during each phase of platform construction. As such, eight or more pieces of heavy 

construction equipment may occupy the temporary work deck at one time. Work associated with 

drilling and installation of the caissons would occur from the temporary work deck at track level,

or from rail-mounted equipment.
June 2021 14-6 

14.5.3.2 DEWATERING AT CASSIONS

Although the drilling for caissons would be deeper than the water table, dewatering would not be 

likely to occur during caisson construction. The Project Sponsor would employ a steel casing with 

a polymer or bentonite slurry to maintain and open holes during drilling until it could install concrete 

via tremie method4

4 Tremie Method, is the most common and expeditious way to place large volumes of concrete to 

considerable thickness under water. Tremie refers to placement of concrete by gravity feed from a hopper 

through a vertical pipe extending above the surface to the underwater floor. As concrete flows from the 

bottom of the pipe, the gravity feed adds more to the hopper so that the tremie pipe is continuously charged

with fresh mix. The major aim in underwater concreting is to place the mix in its final position with as little 

disturbance as possible. As concrete flows from the tremie pipe, it buries the end of the pipe in the mass. 

Gradually the mix flows out toward the edges to fill the concrete forms. As the concrete builds up, its bulk 

raises sufficiently to keep its delivery end buried. The concrete around the end of the pipe seals it from the 

water and prevents aggregate segregation and washing away of cement.

into the caisson. The Project Sponsor would collect and recycle displaced 

slurry between the successive installation of caissons. 

14.5.3.4 TRUCK ROUTING 

The Project Sponsor would employ dump trucks, tractor-trailer rigs, and other vehicles to remove 

demolition debris and excavation spoils from the Project Site and deliver construction material to 

the Project Site. Although the final destination of debris and spoils and the origin of trucks 

delivering materials would be at the discretion of the contractors selected, for purposes of 

environmental impact analyses, FRA has assigned reasonable worst-case assumptions regarding 

probable truck origin/destination according to the items being transported. Construction trucks 

making deliveries and carrying soils and debris from the Project Site would adhere to designated 

truck routes. The duration of trucking activities for the construction of the Preferred Alternative 

would occur over approximately five years, and the hourly number of trucks projected would be 

15–20 trucks during the peak hour for the Platform and 8–10 trucks for the Tunnel Encasement 

during the peak hour. The movement of these trucks would not result in impacts to soils or 

geological formations in the Study Area from construction of the Preferred Alternative. The Project 

Sponsor would oversee:

• Trucking of demolition and excavation debris to destinations west of the Hudson River via the 

Lincoln Tunnel or the George Washington Bridge.

• Deliveries of concrete, likely from a batching plant in Brooklyn, New York, via the BrooklynBattery Tunnel and the West Side Highway.

• Deliveries of diesel and gasoline fuel for on-site equipment, likely from Queens, Brooklyn, or 

the Bronx, New York.

14.6 AVOIDANCE, MINIMIZATION, AND MITIGATION 

MEASURES

The Project Sponsor would undertake measures to avoid, minimize, and mitigate construction 

activities. These various control measures related to geology, soil and foundation construction are 

included in the following subsections. The Project Sponsor would develop the corresponding 

construction guidance documents in advance of construction commencement. The Project 

Sponsor would be responsible for the Project Sponsor’s Contractor implementing the measures 

to avoid, minimize, and mitigate construction activities. 
Chapter 14: Soils and Geology

14-7 June 2021

14.6.1 FUGITIVE DUST CONTROL PLAN

The Project Sponsor would develop a fugitive dust control plan as an element of the CEPP for the 

Preferred Alternative (see Chapter 22, “Mitigation Measures and Project Commitments”). These 

measures would include, at a minimum, the following provisions:

• Controlling fugitive dust through water spraying or use of a biodegradable dust suppressant 

solution; 

• Maintaining large piles of soil, rock or sediment in a wet condition, coated with a dust 

suppressant and/or covered to prevent wind erosion and fugitive dust and covering longerterm stockpiles with weighted tarps. 

• Performing concrete- and rock-grinding, drilling, and saw-cutting operations with a wet blade 

or using mist if the activity is generating significant dust. Such operations in an enclosed space 

would utilize vacuum collection or extraction fans. 

• Stabilizing or wetting loose material during loading and unloading if the activity is generating 

dust plumes, and covering this material during transportation to and from the Project Site and 

Additional Housing Sites.

14.6.2 DEWATERING PLAN

The dewatering plan, which is included as an element of the CEPP for the Preferred Alternative,

would require pumping of dewatering water into sedimentation tanks for removal of sediments 

prior to reuse on the sites or discharge into the City’s sewer system or the Hudson River via the 

existing LIRR outfall that serves the rail yard. The Project Sponsor would periodically test water

and particles in such tanks pH and contaminants. Depending on test results, the Project Sponsor 

would treat the water for contaminants prior to disposal, as per NYSDEC, or NYCDEP regulations, 

and depending on point of discharge (i.e., City sewers or stormwater conveyance pipe to the 

Hudson River). See Chapter 15, “Water and Natural Resources,” for additional information on 

dewatering. 

14.6.3 CONSTRUCTION NOISE AND VIBRATION

Construction practices that would be used to the extent feasible and practicable to reduce noise 

and vibration levels associated with construction of the Preferred Alternative are listed in Chapter 

8, “Noise and Vibration.”

14.6.4 LIRR/MTA COORDINATION

The Project Sponsor would conduct construction work in accordance with LIRR guidelines and 

design/construction criteria, which require persons engaged in pre-construction or construction 

activities located on or near the tracks, or with the potential of fouling a track in the Western Rail 

Yard to attend the LIRR Contractor Roadway Worker and Safety Training in accordance with 

provisions of 48 CFR Part 214 and LIRR Rules and Regulations. LIRR regulations also require 

that MTA and LIRR receive and approve plans—to result in a construction agreement entered into 

between MTA and LIRR and the Project Sponsor—for construction activities related to work at the 

Western Rail Yard. 
June 2021 14-8 

14.6.5 UTILITY PROTECTION

The Project Sponsor has undertaken an inventory of underground utilities on the Project Site 

through a review of existing utility drawings and information, as well as performing geotechnical 

surveys. The Project Sponsor performed this work as part of the engineering and design of the 

Preferred Alternative. The Project Sponsor’s Contractor would confirm location of underground 

utility lines to ensure avoidance by digging test pits at each caisson location. See Chapter 13, 

“Utilities and Energy,” for additional information on utilities. The Project Sponsor’s Contractor 

would likely conduct additional geotechnical surveys if necessary. The Project Sponsor or 

Contractor may conduct additional soil and groundwater testing to characterize more fully soil 

constituents for disposal purposes. 