The Treatment of Biofilm on White Marble Buildings - Webinar

  • Date

    Monday, June 14 2021

  • Time


  • Location


Recent years have witnessed the spread of a black biofilm on the upper reaches of many of Washington's monumental marble buildings. This presentation will highlight two recently completed, high-profile case
studies which involved the treatment and abatement of the biofilm: the Memorial Amphitheater at Arlington National Cemetery (Carrere & Hastings, architect, 1920) and the Thomas Jefferson Memorial (John Russell Pope, architect, 1943). Presenters will explore the scientific process involved in the identification and analysis of biofilm, as well as the advantages and challenges of the two different treatment methods utilized, and the importance of post-treatment analysis and long-term monitoring.


Audrey Tepper is the Historical Architect for the National Mall in Washington, DC, which is part of National Mall and Memorial Parks (NAMA). She has worked for the National Park Service (NPS) for the past 29 years in three separate positions. At the National Mall, she oversees planning, design, and construction on the major memorials, as well as on smaller historic resources within the boundaries of the national park. Her chief responsibility is safeguarding the historic integrity of these nationally and internationally significant sites. Previously, she worked at the NPS’s Technical Preservation Services Division (TPS), where she educated the public on the Secretary of the Interior’s Standards for the Treatment of Historic Properties and guided private-property owners through the Federal Historic Preservation Tax Incentives Program, which grants federal tax credits to eligible properties whose rehabilitations meet the Standards. Audrey earned a
Bachelor of Fine Arts from Cornell University and a Master of Architecture from the University of Virginia. She also studied architectural conservation in Italy and Scotland, with a focus on historic masonry. She is a LEED Green Associate.

Rebecca L. Stevens, AIA, is the first-ever Cultural Resources Manager for Arlington National Cemetery and former Chief Historical Architect for the National Park Service National Capital Region.  She served as chief during the preservation of the Lincoln and Jefferson Memorials and Washington Monument. After practicing architecture throughout the country with the Park Service, she continued her career with architrave pc architects.  Her clients included the U.S. Holocaust Memorial Museum, Smithsonian Institution, and the District of Columbia for whom she rehabilitated historic schools for use as homeless shelters. Ms. Stevens is a graduate of the University of Cincinnati’s School of Design, Art, Architecture, and Urban Planning with a Professional Architecture degree and is a registered architect in California, Colorado, and Maryland. She is a contributing author to numerous technical preservation articles and to Conservation Maintenance for Historic House Museums (2010 AltaMira Press). For many years Ms. Stevens was a guest instructor at the Preservation Institute of Nantucket.  She continues to serve as a trainer for the National Park Service’s preservation training programs. Ms. Stevens is a former President and Board of Directors of the Western and Washington DC Chapters of the Association for Preservation Technology International.

Learning Objectives:

  • Understand the nature and causes of biofilm.
  • Describe methods of managing biofilm
  • Describe the advantages and challenges of different biofilm treatments.
  • Identify the advantages of long- term testing before selecting a treatment and post-treatment analysis and monitoring.