Wednesday, September 23, 2015

Underneath

We frequently respond to inquiries regarding foundations -- researchers want to know what is underneath a given building or monument.

During the 1930s, there was considerable interest in collecting and compiling information related to the geology of New Orleans. Local engineers had long advocated the need for a comprehensive assessment, but it was not until President Franklin Delano Roosevelt created the Works Progress Administration (WPA) that Louisiana had the requisite funds.  The State Board of Engineers endorsed and sponsored WPA projects to document soil and foundations, and to develop accurate elevation datum.

The WPA created the Louisiana Geodetic Survey’s Precise Elevations: City of New Orleans (1937) to record modern datum planes. Prior assessments had been generated by various federal, state and municipal government entities for their own purposes. These data sets proved divergent and did not reflect ground surface settlement changes resulting from early twentieth-century drainage modifications. Precise Elevations set the new WPA datum planes (measured in 1935), compared against the historic data compiled by the Dock Board, the Levee Board, the Sewerage and Water Board, and the United States (Army) Engineering Department.

The WPA’s survey Some Data in Regard to Foundations (1937) was a comprehensive assessment of the variable soil conditions underlying New Orleans, and their effects on historic and contemporary construction. WPA researchers spent two years consulting public and private records, and soliciting anecdotal and illustrative documentation from architects, engineers and builders. They gathered cartographic records, foundation plans, stratigraphic and piling data to chronicle historic construction methods aimed at tackling the city’s alluvial soils. In the process, they measured and rendered the city’s notable structures, including the American Bank Building, the Lakefront (formerly Shushan) Airport, and the U.S. Marine Hospital complex.

The WPA also documented such works as the Robert E. Lee Monument located in Lee Circle at the intersection of St. Charles Street and Howard Avenue.  Alexander Doyle (1857-1922) and Confederate veteran John Roy designed the monument, which was unveiled 22 February 1884.  The WPA estimated that the monument weighed a total of 1,141 tons which was dispersed to its 81 untreated, unpeeled red cypress piles (detail above). Excavation work conducted in 1929 revealed that over half of the piles' lengths (varying from 40-49' feet) were situated below the water line.

Images above:  "Case No. 56. Lee Monument." Some data in regard to foundations in New Orleans and vicinity. Collected and compiled by the Soil and foundation survey as requested by Louisiana engineering society. A project of the Works Progress Administration of Louisiana. New Orleans: 1937, pp. 170-171. Available at Tulane University Libraries.

No comments: