Magnetic and GPR surveys of a former munitions foundry site at the Denver Federal Center

Abstract

We made magnetometer and ground penetrating radar (GPR) surveys over part of the foundation of a World War II-era foundry located on the Denver Federal Center. The site contains a number of highly magnetic source bodies, concrete foundation walls, and underground openings, buried under a clay cap. The cap is several feet thick and has a conductivity of about 35 mS/m, making the features underneath it a poor target for conventional GPR. Indeed, the raw data look unlike typical GPR data, but rather show reverberation (?) bands under sidewalks and other shallow buried sources. Using a newly-written computer package, we made plan maps of the GPR response at different time slices. The sliced GPR data did not outline buried foundry foundations, as we had hoped it might. The resulting plan maps of the sliced data show sidewalks and other blobby features, some of which correspond to magnetometer highs.