WMAL Radio Towers
In the 1960’s and 1970’s, WMAL AM Radio was the king of Washington, DC area news. Their four (4), 400’ tall, free-standing, base-insulated towers occupied an open tract of land in the middle of a residential community in Bethesda, Maryland, just outside the I-495 Beltway and north of the District of Columbia line.
With residential property at an all time high in demand in the Washington, DC suburbs, the idle 78-acre WMAL Towers parcel attracted the attention of residential developer Toll Brothers. They determined that existing zoning would permit them to build 309 high-end homes, a new elementary school and other community amenities to support their new community and enhance property values in the area.
After lengthy negotiation with local regulators and adjacent community representatives, the decision was made to move forward with the project. Geo-Technology Associates, Inc. (GTA), lead engineering company for the project, engaged the services of The Berg Corporation (Berg) of Baltimore, Maryland to clear the radio towers.
Given the height of the towers and their structurally diminished condition, Berg turned to Controlled Demolition, Inc. (CDI) of Phoenix, Maryland, to design, prepare and fell the four (4) towers in a single energetic felling event.
GTA retained Seismic Surveys, Inc. (SSI), a local geotechnical consultant, to do pre-demolition surveys of the 35, pre-existing private homes which surrounded the WMAL Tower site, to monitor the peak overpressure (noise) and vibration from CDI’s felling of the towers, and follow up with a post-demolition survey to confirm that none of the third-party properties were damaged as a result of CDI’s operations.
CDI’s 2-man crew prepared all four (4) towers for felling in eight (8) hours and a 6-man explosives loading crew loaded the structures and placed protective cover to prevent fly of debris, in another eight (8) hours.
Shortly after 9:00 AM on November 4, 2020, CDI detonated less than 3 lb of explosives at the base of each of the four (4) towers to f.ell them sequentially so that they would impact, at grade, on 4-second intervals to minimize noise and vibration arising from the felling of the structures.
Readings taken by SSI at adjacent properties showed vibration and noise levels were a fraction of those permitted by regulatory agencies. No damages were reported or discovered following the felling of the towers.
Berg expects to remove the tower debris in three (3) weeks and will turn the site back over to GTA who will continue to work with the development of the new Toll Brothers’ residential community.