Arthur B. Gelvin

Permafrost Degradation and Subsidence Observations during a Controlled Warming Experiment

Global climate change has resulted in a warmer Arctic, with projections indicating accelerated modifications to permafrost in the near future. The thermal, hydrological, and mechanical physics of permafrost thaw have been hypothesized to couple in a complex fashion but data collection efforts to study these feedbacks in the field have been limited. As a result, laboratory and numerical models have largely outpaced field calibration datasets. We present the design, execution, and initial results from the first decameter-scale controlled thawing experiment, targeting coupled thermal/mechanical response, particularly the temporal sequence of surface subsidence relative to permafrost degradation at depth. The warming test was conducted in Fairbanks, AK, and utilized an array of in-ground heaters to induce thaw of a ~11 × 13 × 1.5 m soil volume over 63 days. The 4-D temperature evolution demonstrated that the depth to permafrost lowered 1 m during the experiment. The resulting thaw-induced surface deformation was ~10 cm as observed using a combination of measurement techniques. Surface deformation occurred over a smaller spatial domain than the full thawed volume, suggesting that gradients in cryotexture and ice content were significant. Our experiment provides the first large field calibration dataset for multiphysics thaw models.

Comprehensive approach for monitoring and remediating petroleum-derived contaminants in the Arctic : case study of the former NARL site near Utqiaġvik, Alaska (formerly Barrow)

The Arctic region of Alaska has a history of petroleum contamination from repetitive fuel spills and the overuse of petrochemicals. Notably, the presence of the former Naval Arctic Research Laboratory (NARL) outside the city of Utqiaġvik, Alaska (formerly known as Barrow), resulted in the contamination of local soils and groundwater with petroleum-derived hydrocarbons. Since the NARL closure in 1987, the U.S. Navy (primarily) has implemented many environmental investigations, remediation, monitoring, and containment strategies. However, the soil and subsurface soil unique to the Arctic complicates traditional remediation techniques as a result of the harsh environment and underdeveloped infrastructure of the remote site. Bioremediation and stimulating the existing microbial community represent attractive methods of decontamination because they are nontoxic and relatively easy to implement. The results from this study offer a comprehensive approach for characterizing petroleum-derived contamination specific to Arctic regions by coupling nondestructive geophysical tools with in situ hydro-biogeochemical methods. The overall goals of this project were to investigate the surface and subsurface soil properties at the former NARL site for the Naval Facilities Engineering Command Northwest, monitor the distribution of hydrocarbons, characterize petroleum-derived hydrocarbons, and test various bioand phytoremediation scenarios both in the laboratory and as a field study. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR. ERDC/CRREL TR-18-18 iii