October 2025 ASCE Anchorage Branch Luncheon

LOCATION: OCTOBER LUNCHEON AT CRW in CONFERENCE ROOM 1A

Steven Halcomb, PE, GE, BC.GE, of Devise Engineering and Ori Miller, PE, of Northern Utility Services will present on "Depth of Frost Analysis in Southcentral Alaska".

Abstract: Within Anchorage and around much of southcentral Alaska, standard practice is to bury water lines at 10 feet deep for frost protection. While 10 feet of cover is generally considered adequate, the actual depth of frost penetration can vary significantly with local soil conditions, groundwater level, and type of backfill above buried utility infrastructure. A deeper burial depth is achievable under greenfield construction conditions; however, attaining deeper excavation depth can be significantly more challenging when other competing utilities must be avoided and construction must be performed in tight, predeveloped areas. Northern Utility Services proposes utilization of a more targeted approach to determine the appropriate depth of water line burial. The proposed approach evaluates sites on a case-by-case basis, looks at local conditions, and incorporates usage of insulating foam when appropriate as an equivalent substitute for backfill thickness for thermal protection. Targeted evaluations could save significant construction costs on deep excavations in areas which may or may not have deep frost penetration depths.

Northern Utility Services is working with Devise Engineering to develop a software tool to assist designers in evaluating sites to determine how deep to install buried infrastructure. The Stephan-Bergren method of frost penetration analysis presents a method of evaluating multi-layered systems to estimate depth of frost penetration in varying soil conditions. The BERG2 program was developed in the 1980s using FORTRAN code. Devise Engineering is working in conjunction with Northern Utility Services and is making an effort to update the program to a more modern format and publish the updated code to be publicly available for designers to use and assist performance for a more targeted depth of frost analysis.

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