Understanding geologic features can influence design and construction practices because certain geologic features are considered resources while others are considered potential hazards. This chapter identifies geologic resources that are intersected by the Representative Route of the Preferred Alternative.
Volume 2, Section 7.7, defines and discusses geologic resources and geologic hazards. Geologic resources include sole source aquifers, naturally occurring minerals, and active/inactive mines. Geologic hazards include seismic hazards (active geologic faults or fractures), karst terrain (characterized by sinkholes and caves), unstable soils (landslide susceptibility), naturally occurring asbestos, and acid producing soils. With regard to Environmental Consequences, the Preferred Alternative may affect geologic resources, but geologic hazards may also affect decisions about the location, design, and construction methods for the Preferred Alternative. Effects would depend on the type of geologic resource or hazard present and construction method proposed. Depending on construction type, effects on geologic resources or hazards would be generally associated with earth-moving construction activities such as drilling, boring, and earth removal. For example, tunneling would have a higher likelihood of affecting a geologic feature (such as sole source aquifers) than at-grade construction activities. However, given the level of detail regarding construction activities and alignments being analyzed for this Tier 1 Final Environmental Impact State (Tier 1 Final EIS) and generalized locations of the geologic resources and hazards, the Federal Railroad Administration (FRA) did not identify site-specific effects. Refer to Volume 2, Appendix E.07, for the detailed methodology describing how geologic resource effects were analyzed.
During the Tier 1 Draft EIS comment period, the U.S. Environmental Protection Agency requested more information and analysis with regard to effects on public and private drinking water supplies. Section 7.7.4 includes effects on sole source aquifers, which supply drinking water to many areas within the Affected Environment. Section 7.7.9 provides recommendations on understanding effects on public and private drinking water supplies during Tier 2 project studies. In addition, Chapter 7.5, Hydrologic/Water Resources, provides a list of water bodies, some of which may serve as drinking water supplies based on their water quality designation. Chapter 7.19, Summary of Public Health Effects, also addresses potential effects on drinking water supplies.
Within the Affected Environment, the following geologic resources and hazards occur (see Volume 2, Appendix E.07, for a description of these geologic resources and hazards):
These occurrences are generally consistent with what occurs within both the Existing NEC + Hartford/Springfield Line and Preferred Alternative; the exception is that karst terrain does not occur within the Existing NEC + Hartford/Springfield Line.
The FRA analyzed the Affected Environments for the Existing NEC + Hartford/Springfield Line and the Preferred Alternative for the existence and/or occurrence of geologic resources and geologic hazards. Appendix EE.07 notes these geologic features by state and county.
Notable resources within the Affected Environments include sole source aquifers, naturally occurring asbestos, karst terrain, and soils associated with moderate or high landslide susceptibility. The former two resources are notable to highlight within the Affected Environments because they may represent significant regulatory challenges. The latter two resources are notable to highlight within the Affected Environments due to potential associated safety issues and engineering costs related to construction.
Sole source aquifers supply drinking water to many areas within the Affected Environment and occur in the following locations within the No Action Alternative and Preferred Alternative:
Naturally occurring asbestos exists in soils within the Affected Environments of the No Action Alternative and the Preferred Alternative in Baltimore City, MD, and Hudson County, NJ.
Karst terrain occurs within the Affected Environment in Baltimore and Harford Counties, MD, for the Preferred Alternative.
Soils associated with moderate or high landslide susceptibility occur within the Affected Environments of the Existing NEC + Hartford/Springfield Line and the Preferred Alternative in Baltimore, Baltimore City, Harford, and Cecil Counties, MD; New Castle County, DE; Delaware, Philadelphia and Bucks Counties, PA; Hartford County, CT; and Hampden and Suffolk Counties, MA.
As discussed in the previous section, this analysis highlights where the Existing NEC + Hartford/Springfield Line and Preferred Alternative intersect with certain geologic resources and hazards - including sole source aquifers, soils associated with moderate and high landslide susceptibility, naturally occurring asbestos, and karst terrain. These four geologic resources and hazards may present significant regulatory challenges or potential associated safety issues and engineering costs related to construction. Appendix EE.07 includes an inventory of a larger set of geologic features (listed by state and county) that the Existing NEC + Hartford/Springfield Line and Preferred Alternative would intersect.
The Existing NEC + Hartford/Springfield Line and the Preferred Alternative would intersect sole source aquifers in the following locations, including all states except Maryland and the District of Columbia:
The Preferred Alternative would also intersect sole source aquifers in New York and Kings Counties, NY.
The Existing NEC + Hartford/Springfield Line and the Preferred Alternative would intersect soils associated with moderate or high landslide susceptibility in the following areas:
The Preferred Alternative would also intersect soils associated with moderate or high landslide susceptibility in Delaware and Philadelphia Counties, PA.
Karst terrain occurs only within Harford County, MD, within the Preferred Alternative. In addition, naturally occurring asbestos does not exist within the Existing NEC + Hartford/Springfield Line or the Preferred Alternative.
Since the Existing NEC + Hartford/Springfield Line is incorporated in whole within the Preferred Alternative, the following describes the effects of new or upgraded segments proposed under the Preferred Alternative on geologic resources.
Elements South of New York City
Elements North of New York City
As described in Volume 2, new stations would likely affect geologic resources or encounter geologic hazards more than modified stations. Table 7.7-1 presents proposed new stations or modified existing stations that geographically coincide with resources and hazards that may present significant regulatory challenges, potential associated safety issues, and engineering costs related to construction, or other potential geographic conflicts that would need to be assessed. The resources include sole source aquifers and mineral resources. The hazards include soils associated with moderate or high incidences of landslide occurrences, naturally occurring asbestos, and karst terrain. As shown in Table 7.7-1, no effects associated with naturally occurring asbestos or karst terrain would occur as a result of new stations or modifications to existing stations.
|State||County||Station ID||Station Type||Station Name||Geologic Resource/Hazard||Presence|
|MD||Baltimore City||13||New||Bayview||Landslide Susceptibility||X|
|DE||New Castle||26||New||Newport||Landslide Susceptibility||X|
Sole Source Aquifer
|PA||Delaware||34||New||Baldwin||Sole Source Aquifer||X|
|44||Philadelphia Airport||Sole Source Aquifer
|NJ||Mercer||61||Modified||Princeton Junction||Sole Source Aquifer||X|
|Hartford / Springfield Line|
|CT||Hartford||186||New||West Hartford||Landslide Susceptibility||X|
Conditions within the Context Area are similar to those described for the Affected Environment. In addition to the geologic resources and hazards described in Section 7.7.3, soils potentially containing naturally occurring asbestos also exist within the Context Area in Delaware, Philadelphia, and Bucks Counties, PA.
The Preferred Alternative shares some similarities with the three Action Alternatives (which are described in Volume 2, Section 7.7) but also differs in some locations. Some notable similarities and differences include the following:
Programmatic mitigation measures could include design considerations, alternative construction methods, and slope/soil stabilization measures. Depending on the affected geologic resource, specific mitigation measures could include the following:
More-detailed analysis and subsurface test will be required during Tier 2 analyses to confirm geologic conditions that may affect engineering, design, and costs. During the public comment period, the U.S. Environmental Protection Agency requested that more information and analysis be included in regards to effects on public and private drinking water supplies for the Tier 2 project studies. Detailed groundwater and surface water source studies and more-specific construction methodology mitigation measures will be included as part of Tier 2 project analysis. Additional analysis will include potential impacts on public and private drinking water supplies, including where the Preferred Alternative may cross surface water and groundwater drinking water sources or potential sources of drinking water. Any state or federally defined Source Water Protection Areas (for both surface water and groundwater) - including sanitary protective areas for any public water supply located within the Preferred Alternative - will be defined. The Tier 2 project analysis will include coordination with the EPA, appropriate state resource representatives, and the U.S. Geological Survey.