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- 2.1 -
Historical Research

  From historical documents and information gathered from residents of the City of Wilmington, Tetra Tech developed a listing of the city's tanneries. Historical references included the Baist Atlas of 1901, the G.W. Beers Atlas of 1868, the G.W. Hopkins C.E. Survey of 1876, the Franklin Survey Co. Atlas of 1936 and the Sanborn Map Company Fire Insurance Maps of 1884, 1901, 1927, 1948 and 1967-1984. Atlases were obtained from the Delaware Historical Society, University of Delaware Morris Library and the City of Wilmington Planning Department. While a substantial list, it must be understood that research of this type can provide good information on many tanneries, but cannot guarantee that all tanneries have been identified. Multiple overlapping tannery data were sorted and grouped into related tannery operations according to ownership and geographic similarities.

  The largest part of this effort was thoroughly examining every available map within these historic atlases. A conservative approach governed the investigation, intended to provide a more complete list of tannery operations rather than to exclude possible tanneries. Once a tannery or tannery-related industry was identified, the map was digitally scanned (where possible) or photocopied for future analysis.

  Tanneries typically overlapped on multiple information sources. To identify unique tannery operations a tracking number was assigned to catalogue each scan by year and tannery. On the scanned image the tannery location was identified with an arrow, and the outline of tannery-related structures and storage areas as illustrated on the document was entered into a GIS layer. Copies of these scanned maps are included in Section 3 for each site. At the conclusion of the historical investigation, nine digital data layers (one for each data source) were merged into a single GIS file for a total of 164 tannery outlines. Based on their locations these outlines were grouped and identified with codes (some previously established by DNREC to track environmental sites). This methodology produced a total of 53 clusters subsequently referred to as tannery sites.

  DNREC investigation/remediation were ongoing or complete at some tanneries. Investigation and remediation coincident with tannery locations were identified by DNREC SIRB and provided to Tetra Tech as outlines on land parcel boundaries. These outlines were added to the existing GIS as a separate digital data layer and classified as either "Completed" or "In Progress."

- 2.2 -
Field Investigation

  A "windshield survey" to each tannery site identified multiple characteristics that would influence site prioritization, including:

  • Presence of children
  • Current land use
  • Current business occupant, if obvious from the windshield survey
  • Surrounding land use
  • Uncovered soil
  • Covered/paved areas
  • Address information
  • Possible sampling locations

Area of subsidence/collapse identified on Site T52 that appears to coincide with historical building outlines. The road into the parking area (foreground) has subsided over 2' on one side.

  On subsequent visits original observations were verified and photographed to capture the general appearance of the area and document exposed soil. Tetra Tech visited every tannery site on at least four separate occasions.

2.3 Site Prioritization