Understanding geologic features can influence design and construction practices because certain geologic features are considered resources while others are considered potential hazards (see Section 18.104.22.168).
This chapter identifies geologic resources that are intersected by the Representative Routes of the Tier 1 Draft Environmental Impact Statement (Tier 1 Draft EIS) Action Alternatives. Appendix E, Section E.07, provides both the effects-assessment methodology that was used to evaluate geologic resources and hazards and the data supporting the analysis.
Geologic resources and hazards are defined below and include descriptions of the different types of geologic resources and hazards assessed in this Tier 1 Draft EIS:
Appendix E, Section E.07, provides more-detailed definitions of geologic resources and hazards.
The Federal Railroad Administration (FRA) developed an effects-assessment methodology for each of the resources examined in this Tier 1 Draft EIS. The effects-assessment methodology defines each resource and data source, and explains how the Affected Environment was defined and established and how the effects on each resource were evaluated and reported. Table 7.7-1 summarizes key factors associated with the effects-assessment methodology for examining effects on geologic resources and construction constraints caused by geologic hazards.
|Resource||Affected Environment||Type of Assessment||Outcome|
|Geologic Resources||3,000-foot-wide swath centered along Representative Route for each Action Alternative||
||Identification of the presence of geologic resources within the Affected Environment and intersected by the Representative Routes.|
The southern portion of the Study Area can be geographically characterized by a mix of low-lying areas and gentle changes in topography that transition to higher elevations and sharper changes in topography in the north. Notable geologic features in the Study Area include the Chesapeake Bay, Long Island Sound, and Appalachian Mountains.
With regard to Environmental Consequences, the Action Alternatives may affect geologic resources, but geologic hazards may also affect decisions about the location, design, and construction methods for any of the Action Alternatives. Effects would depend on the type of geologic resource or hazard present and construction method proposed. Depending on construction type, effects 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 Draft EIS and generalized locations of the geologic resources and hazards, the FRA did not identify site-specific effects.
Although different types of geologic resources and hazards (as defined in Section 22.214.171.124) are present within the Affected Environment and within the footprint of the Action Alternatives, only certain resources and hazards are highlighted in this section. The resources and hazards highlighted 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. Appendix E, Section E.07, includes an inventory of the larger set of geologic features (listed by state and county) within the Affected Environment and that are intersected by the existing NEC and Action Alternatives.
The FRA analyzed the Affected Environment for the existing Northeast Corridor and each Action Alternative for the existence and/or occurrence of geologic resources and geologic hazards. Appendix E, Section E.07, notes these geologic features by state and county.
Notable resources within the Affected Environment 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 Environment because they may represent significant regulatory challenges. The latter two resources are notable to highlight within the Affected Environment 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:
||Existing NEC and all Action Alternatives|
||Alternative 3 (New York City to Hartford via Long Island)|
Naturally occurring asbestos exists in soils within the Affected Environments of the existing NEC and all Action Alternatives in Baltimore City, MD, and Hudson County, NJ.
Karst terrain occurs within the Affected Environment in Baltimore and Harford Counties, MD, within Alternative 3.
Soils associated with moderate or high landslide susceptibility occur within the Affected Environments of the existing NEC and all Action Alternatives in Washington, D.C., and Prince George's, Anne Arundel, Howard, and Baltimore Counties, MD. Additionally, these soils occur within the Affected Environment of Alternatives 2 and 3 in Hartford County, CT, and Suffolk County, NY, in the New York City to Hartford via Long Island route option of Alternative 3.
This analysis highlights where certain geologic resources and hazards-including sole source aquifers, soils associated with moderate and high landslide susceptibility, naturally occurring asbestos, and karst terrain-intersect with the existing NEC and the Representative Route for each Action Alternative. These four geologic resources and hazards may present significant regulatory challenges or potential associated safety issues and engineering costs related to construction. Appendix E, Section E.07, includes an inventory of a larger set of geologic features (listed by state and county) that are intersected by the existing NEC and Action Alternatives.
Table 7.7-2 and Table 7.7-3 present areas where the Representative Routes intersect sole source aquifers and soils associated with moderate or high landslide susceptibility. The potential exists for the existing NEC and all the Action Alternatives to encounter these geologic resources and hazards. In addition, karst terrain exists only in Harford County, MD, within the Representative Route of Alternative 3, and no soils that contain naturally occurring asbestos exist within the existing NEC or Representative Routes of any of the Action Alternatives.
|Geography||Geologic Resource/Hazard||Existing NEC||Alternative 1*||Alternative 2*||Alternative 3*|
|DE||Sole Source Aquifer||X||X||X||X|
|PA||Sole Source Aquifer||X||X||X||X|
|NJ||Sole Source Aquifer||X||X||X||X|
|NY||Sole Source Aquifer||X||X||X||X|
|Sole Source Aquifer||X||X||X||X|
|RI||Sole Source Aquifer||X||X||X||X|
|MA||Sole Source Aquifer||X||X||X||X|
|Geography||Geologic Resource/Hazard||Existing NEC||Alternative 3|
|D.C. to NYC||New York City to Hartford||Hartford to Boston|
|via Central Connecticut||via Long Island||via Providence||via Worcester|
|DE||Sole Source Aquifer||X||X||—||—||—||—|
|PA||Sole Source Aquifer||X||X||—||—||—||—|
|NJ||Sole Source Aquifer||X||X||—||—||—||—|
|NY||Sole Source Aquifer||X||—||X||X||—||—|
|Sole Source Aquifer||X||—||X||X||X||X|
|RI||Sole Source Aquifer||X||—||—||—||X||X|
|MA||Sole Source Aquifer||X||—||—||—||X||X|
New stations would likely affect geologic resources or encounter geologic hazards more than modified stations. Table 7.7-4 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 incidence of landslide occurrences, naturally occurring asbestos, and karst terrain. As shown in Table 7.7-4, no effects associated with naturally occurring asbestos or karst terrain would occur as a result of new stations or modifications to existing stations.
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, a sole source aquifer exists in Fairfield County, CT, only in the Context Area of Alternative 3 (New York City to Hartford via Central Connecticut route option). Soils potentially containing naturally occurring asbestos also exist within the Context Area in Delaware, Philadelphia, and Bucks Counties in Pennsylvania.
|State||County||Station ID/Type||Station Name||Geologic Resource/Hazard||Alt. 1||Alt. 2||Alt. 3|
|MD||Anne Arundel||5/Existing||Odenton||Landslide Susceptibility||X||X||X|
|6/New||BWI Airport||Landslide Susceptibility
|Baltimore City||11/New||Baltimore Downtown||Mineral Resources||X|
|DE||New Castle||28/New||Edgemoor||Sole Source Aquifer||X||X||X|
Sole Source Aquifer
|46/New||Philadelphia Market East||X|
|NJ||Mercer||61/Existing||Princeton Junction||Sole Source Aquifer||X||X||X|
Sole Source Aquifer
|CT||Hartford||164/New||Hartford (New)||Landslide Susceptibility||X||X|
|RI||Washington||123/Existing||Westerly||Sole Source Aquifer||X||X||X|
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:
Tier 2 analyses would determine the presence and type of geologic resources to a higher level of detail, as well as assess the need for and identify mitigation measures and design and construction methods that would avoid or minimize effects. Coordination with the EPA and the U.S. Geological Survey may be warranted when more site-specific effects are known.
1 Inactive mines were not included in the analysis because of the lack of complete and timely data. The Tier 2 process would perform additional analysis.
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