Originally Posted by mccary
I don't know about that event causing magnetic disturbances, but I think the are filling Poplar Island with dredge sediment (when they dredge channels) and I would guess that the sediment contains varying amounts of magnetic deposits... I remember the old Poplar Island back in the 70s as a wonderful place to anchor with a shallow draft boat.
He makes an excellent point. Beth Steel (now ISG) at Sparrows Point discharged VAST amounts of pickle liquor for many years, until they finally began treating this material, I think in the early 70s. The liquor was basically ferric sulfate in acid water, which would become rust upon contact with Bay water. The material would take time to settle and was well know for causing serious silting issues in the area. (I used to do some engineering related to the treatment plant... but you really don't want to know how much COD was and still is discharged).
But I don't know about the actual content of the dredge spoil or the compass issue.