Brief Review of Geotechnical / Geological
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BRIEF REVIEW OF GEOTECHNICAL / GEOLOGICAL ASSESSMENTS OF JANUARY 2021 DRAFT ENVIRONMENTAL IMPACT STATEMENT (DEIS) BALTIMORE-WASHINGTON SUPERCONDUCTING MAGNETIC LEVITATION (SCMAGLEV) PROJECT Created For City of Greenbelt, Maryland Dr. Burak F. Tanyu 1 April 19, 2021 1 Associate Professor of Geotechnical/Geotransportation Engineering in the Civil, Infrastructure, and Environmental Engineering Department of George Mason University. Prior to joining George Mason, Dr. Tanyu worked as a senior geotechnical engineer in private industry. Dr. Tanyu’s resume is attached to this report as Attachment A. 1 This brief review is written to provide a quick overview of the content included in the detailed review for the City of Greenbelt (City). The detailed review is provided as a separate document. The purpose of these reviews is to provide an assessment of the geotechnical / geological content of the January 2021 draft environmental impact statement (DEIS) that was released by the U.S. Department of Transportation’s (USDOT) Federal Railroad Administration (FRA) and Maryland Department of Transportation (MDOT) for the Baltimore-Washington Superconducting Magnetic Levitation (SCMAGLEV) project. Overview of the SCMAGLEV Project The SCMAGLEV system in the DEIS refers to a high-speed train system that runs on a fixed guideway (with no traditional railway but instead a designated pathway) powered by magnetic forces that is capable of traveling at speeds of over 300 miles per hour. Once the SCMAGLEV is in operation, it is stated that the trains will be in service 365 days per year between the hours of 5:00 am and 11:00 pm. The construction of such system along this route is anticipated to take 7 years. The DEIS outlines two possible routes (referred as alignments) for the train system: • J alignment: This proposed alignment is reported to consist of 25% viaducts and 75% tunnels. • J1 alignment: This proposed alignment is reported to contain 14% viaducts and 86% tunnels. Within the limits of the City, the project appears to be a combination of what is referred as deep tunnels (identified in the DEIS as the separation between the top of the tunnel and the ground surface to be more than 50 ft) and the transition zone where the separation becomes shallower. Within the limits of the Beltsville Agricultural Research Center (BARC), there is a transition zone from the tunnel to the ground surface and then the majority of the project appear to be through viaducts. Within the City and BARC, both the J and J1 alignments are very close to each other in their locations. As is discussed in more detail in the Detailed Review document (See Commentary-6) it is not clear why the J1 alignment transition from deep tunnel to the shallower tunnel was selected to occur right around a well-established residential area and how such consideration was justified based on geotechnical and geological information. Additionally, the tunnel construction details provided in the DEIS for this type of tunnel portal construction does not specify which proposed construction type might be used at this site, therefore it is not clear whether the ground will be excavated and if so, will there be open cut portal sections, cut and cover sections, or something else. See Appendix G02, TY-6. The DEIS indicates that along the proposed alignments, maintenance and repair facilities associated for the train systems (trainset maintenance facility - TMF) and for the guideways (maintenance of way - MOW facility) are also required to be constructed. In terms of the locations of these facilities, the DEIS provides six alternatives for each alignment. However, in terms of the impact to the City and BARC, only three alternative combinations are relevant and 2 these options are the same for both alignments. These three alternative locations for the TMF and MOW facilities can be summarized as: • BARC west alternative (located within the west side of the BARC property and west of the Baltimore-Washington Parkway); • BARC airstrip alternative (located within the east side of the BARC property and along the decommissioned airstrip located within the BARC property); and • MD 198 alternative (located within a property that is outside of BARC and City limits). Although the DEIS was released by FRA and MDOT, it is stated in the DEIS that the Baltimore- Washington Rapid Rail, LLC (BWRR) (a private Project Sponsor) will be the entity that would design, construct, and operate the SCMAGLEV system. The preferred configuration of the train system by BWRR have been outlined in the DEIS as: • J alignment; • BARC west alternative for the TMF and MOW facilities, and • Termination of the train system at Cherry Hill south of I-95 close to Baltimore (outside the limits of the City and BARC). The DEIS explains the BWRR’s preferred alternative was selected because it would require shorter construction time, increases the ability to avoid and mitigate impacts, and lowers construction and operating costs. Although BWRR’s preferred alternative has been outlined in the DEIS, the DEIS includes information regarding both J and J1 alignments. The DEIS is very comprehensive. It includes five chapters and seven appendices, and sub- appendices within appendices that entail hundreds of pages. Overall, many details that would be expected from a comprehensive planning study have been incorporated in the DEIS. Considering that the purpose of this review written for the City is to provide an assessment of the geotechnical / geological content of the January 2021 DEIS, it is important to summarize in this executive summary the content within DEIS as it relates to these subjects and the associated gaps. Such summaries are provided below. Geotechnical and Geological Content of the DEIS The DEIS has the following sections as it relates to geology and geotechnical engineering: • Chapter 4, Section 4.13, Topography and geology; • Chapter 4, Section 4.14, Soils and farmlands; and • Appendix G13, Preliminary geotechnical engineering assessment report. The content of these sections include depictions of site-specific subsurface investigations (borings) at twenty-three locations (along the roughly 40 miles distance), interpretation of continued longitudinal subsurface sections along the profile where borings were performed (created by two different firms), sixty nine laboratory index tests of soil samples obtained from 3 subsurface, extensive literature review of the regional geology, and generic information regarding possible construction methods. Key findings from the DEIS as it relates to the overall geology of the project site for the entire distance between Washington D.C. and Baltimore are as follows: • Index property tests indicate presence of at least three different soil types in the region and presence of bedrock. Literature review discussed in the DEIS indicates that the properties of these soils and bedrock as it relates to possible engineering properties may vary greatly from each other within the region; • Water levels observed from the subsurface investigations confirm that most of the tunnel depths will be constructed in zones below groundwater; • Geology, in terms of aquifer systems and consistency of the soil units throughout the region are complex and may vary from one location to another; • Some soils in the region are susceptible to slope instabilities (landslides), erosion, and swelling as well as may contain electrochemical and chemical properties that may be a risk to corrode/weaken concrete and steel (materials that may be used during construction of the project). Gaps in the DEIS As It Relates to Geological and Geotechnical Considerations The following paragraph has been copied directly from the Section ES 1.4 of the DEIS: “The DEIS provides a detailed description of the SCMAGLEV Project Purpose and Need, alternatives developed, the existing environmental conditions and the analysis of the potential beneficial and adverse environmental effects and consequences of the alternatives, and potential mitigation strategies. The DEIS provides a comparative analysis between the No Build Alternative and the Build Alternatives so that government agencies, elected official, interested citizens, businesses, and other stakeholders can assess the potential human and environmental effects of the SCMAGLEV Project.” The purpose of copying the above citation into this brief summary is to outline that it is stated in the DEIS that a comparative analysis has been provided for the people to assess the potential human and environmental effects. However, it is not clear from what has been provided in the DEIS how the alignments and alternatives have been evaluated in detail in terms of the geological and geotechnical impacts that may potentially create a risk for humans, infrastructures, and environment. The primary gap associated with this concern starts from the elimination of 14 different alignment alternatives to almost two similar alignments. It is not clear how the DEIS team evaluated the geotechnical and geological risks for each of the 14 previously considered alignments during the evaluation of the alternatives. For example, from the presented information in the DEIS, some of the previously eliminated alignments could have allowed the tunnels to be constructed through bedrock layers that were shallower in depth. This condition 4 appears to change in other alignments. Such comparisons, for example, could have allowed the specific discussions between the alignments in terms of the effects of surface settlements, facing stability issues