Forensic Engineering Analysis of Residential Underdrain Design Methodologies, Performance, and Failures


  • Edward Fronapfel, PE, DFE SBSA, Inc.



underdrain, foundations, cleanouts, common interest ownership community, homeowners association, video inspection, sump, calcite, pipe blockages, forensic engineering, Phoenix


In 2014, the basement of a single-family home in a residential subdivision flooded. The homeowner’s insurance company engaged an engineer to conduct forensic investigations, which ultimately determined that the resultant flooding was caused by blockage of an underdrain system to which the home was connected. This system included a main line in the street and a lateral that connected the underdrain to the home’s foundation drain. Subsequent to this event, other homes in the subdivision reported flooding in the basements and crawlspaces. The author was engaged by the subdivision homeowners association (Common Interest Ownership Community or CIOC). The CIOC’s declarations and recorded documents contained no information regarding the existence of the underdrain system. In addition, there was no clear information about the ownership or maintenance responsibility. The author’s field investigations determined the underdrain was not constructed to the applicable minimum standards, and the developer did not provide adequate flow capacity for the number of homes served by the underdrain. The CIOC entered into litigation against the developer, and the author evaluated issues associated with the design, construction, transition, and maintenance of the underdrain system.

Author Biography

Edward Fronapfel, PE, DFE, SBSA, Inc.

Edward L. Fronapfel is the Owner and President of SBSA, Inc., a Golden, Colorado-based forensic engineering company. He is a licensed Professional Engineer in more than 35 states. Ed’s experience allows him to see a project in a complete setting and understand the complex interaction between the geotechnical, structural, architectural, and thermal environments. Ed’s civil engineering background includes geohydrology, hydrology, hydraulics, site design, and evaluation of existing structures. His structural background includes new design and quality assurance of industrial systems, residential, and commercial properties. Ed continues his commitment to the building community by serving as an Adjunct Professor at the University of Denver as well as teaching and writing for local and national organizations. Ed also serves on the Board of Review for Jefferson County, Colorado and is a highly experienced expert witness, having given testimony at more than 400 depositions and trials.




How to Cite

Fronapfel, Edward. 2021. “Forensic Engineering Analysis of Residential Underdrain Design Methodologies, Performance, and Failures”. Journal of the National Academy of Forensic Engineers 37 (1).