Phase 1B Underwater Archaeological Report for the Onondaga ...

FINAL
Phase IB Underwater Archaeological Resources Report for Onondaga Lake Superfund Site
4. Simultaneous with 3 above, the locations of shallow water sonar anomalies were cross-referenced
with those locations on Google Earth® and Microsoft® Virtual Earth to determine if there were visible
shoreline or shallow-water features that could identify the contact.
5. Simultaneous to 3 and 4 above, historic navigational charts and maps were examined to determine if
there were charted historic features that could yield such an anomaly.
6. The analysis resulting from steps 2-5 was recorded in tabular form and in expanded form and
presented in the Underwater Work Plan.
The Underwater Work Plan, in addition to outlining the locations of potential archaeological sites, also
prescribed the tools and methods to be used for the Phase 1B fieldwork.
PHASE 1B REMOTE SENSING METHODOLOGY
The remote sensing fieldwork outlined in the Underwater Work Plan was executed from June 2 to 11,
2010. The fieldwork was directed by LCMM, with CRE providing the survey vessel and captain, and the
remote sensing equipment and technician. The fieldwork was executed by Adam Kane (LCMM,
Archaeological Director), Chip Ryther (CRE, Oceanographic Operations Manager), Shipherd Densmore
(CRE Survey Vessel Captain), Eli Perrone (CRE Oceanographic Technician), Bill Campbell (CRE ROV Pilot),
and Christopher Wright (CRE Senior Hydrograpaher). Safety oversight was provided by Parsons through
Dale Dolph, Kelly Miller and Xiaodong Huang.
The following methodological approach was used to collect side scan sonar, scanning sonar and
videographic data sets from each anomaly in or adjacent to a remediation area.
Side Scan Sonar
Side scan sonar data was acquired with an Edgetech Model 4125-P 400/1,250 kHz side scan sonar, and a
Hemisphere VS-100 differential Global Positioning System (DPGS) and digital compass (Figure 24). The
sonar and differential global positioning system (DGPS) were interfaced to a laptop computer running
Edgetech Discover data acquisition software via Ethernet and serial connections, respectively.
HYPACK hydrographic data acquisition and navigation software was used to design a series of survey
transects centered on each anomaly. When possible, these transects were extended to expedite
insonification of nearby pairs or groups of anomalies. Transect spacing was set to 25 feet (7.6m) to
accommodate the short ranges of the high frequency signals while ensuring approximately 200%
coverage of each anomaly. A separate navigation computer was set up to provide a steering display for
the vessel pilot.
The sonar towfish was deployed from the bow of CRE’s 26 foot (7.9m) survey vessel Lophius, using the
vessel’s A-frame and hydraulic winch (Figure 25). Because the majority of the anomalies were located in
shallow water (less than 10-feet [3.1m] deep), a minimal length of tow cable was deployed. This short
cable length was recorded to facilitate correction of offsets between the DGPS antenna and the towfish.
Side scan sonar data were acquired using a 1,250 kHz signal. Sonar swath width settings (per channel)
ranged from 33 to 82 feet (10 to 25m). Digital data were recorded in both Edgetech’s .JSF format and
standard .XTF format. Data were archived to external hard drives at the end of each survey day.
Navigation and data acquisition around many near-shore anomalies were hampered by dense aquatic
vegetation. In some instances, this vegetation completely obscured data surrounding the anomaly.
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