Apr 10, 2016

Long Postponed Investigation of POI 2 Comes Up Empty-Handed

In January1993, the first discovery of munitions in Spring Valley was made on 52 Court, NW, when a backhoe operator excavated part of the disposal pit, exposing munitions items.  At that location, there were circular trenches that were used for munitions testing during the World War I era ... When USACE began investigating and reestablishing the history of the American University Experiment Station (AUES), USACE noticed a very similar set of trenches existing on Sedgwick. The Sedgwick Trenches became "Point of Interest" (POI) 1 in the site conceptual model of what needed to be further investigated in Spring Valley. POI 2, 3, and 4 were areas immediately adjacent to Sedgwick Trench, where aerial photography suggested the existence of disposal features. During the remedial investigation, USACE was able to investigate POI 3 and 4, but not POI 2. After 2012, USACE reestablished communication with the property owner at 3700 Block of Fordham Road, where property POI 2 is located. USACE was able to gain access to the property to intrusively investigate POI 2 within the last few weeks. 
In 2003, two geophysical surveys were conducted at this property; an Electromagnetic (EM) survey and a Magnetic (MAG) survey. The EM survey showed two clusters of single point anomalies in the front yard. A "possible pit" feature was seen on the MAG survey, but not on the EM survey. Although there may be some error in the aerial photograph from 1918, the location of the "possible pit" feature shown in the MAG survey very closely matches the location of a "possible pit" ground scar on the 1918 map, causing this area to be of more interest to the Army Corps ... The MAG survey can be more sensitive, and can scan deeper into the ground. Anomalies do not show up on an EM survey if they are buried very deep. So there might be a disposal pit full of World War I bombs made out of metal, which could be an explanation as to why the anomalies show up in the MAG Survey but not in the EM survey ..

USACE went back to the property in March. The large anomaly was intrusively investigated in two locations ... Once these holes were excavated to four feet, the geophysical instruments were inserted into the holes. The instruments did not detect a signal at the bottom of either hole. When the instruments were brought up the side of the hole near the surface, the signal returned. The conclusion is that something about the soil structure in this area causes a magnetic signature. The signal happens near surface, in the first foot or two. However, there were no more magnetic signals at the bottom of the holes. USACE [now] believes that this large anomalous area, which was designated as POI 2, is due to what is referred to as “hot soil” or “hot rocks,” not buried metal.

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