305 West Grand Avenue, Suite 300 Montvale, New Jersey 07645 Phone 201.930.9890 Fax 201.930.9805 www.anchorqea.com M EMORANDUM To: Caroline Kwan and Nica Klaber U.S. Environmental Protection Agency Region 2 Date: From: Amy Corp, Anchor QEA, LLC Project: 120782-01.01 Cc: Jim Quadrini and Tom Schadt, Anchor QEA, LLC Re: FSAP Addendum No. 4 Supplemental Bathymetric Survey Data Collection This addendum to the Field Sampling and Analysis Plan (FSAP; Anchor QEA 2011a), which was approved by the U.S. Environmental Protection Agency (USEPA) on October 28, 2011, presents an addition to Section 4.2.2 Hydrographic Surveys and describes the procedures that will be followed to perform a supplemental bathymetric survey to evaluate where and to what degree the October 2012 storm Sandy may have altered sediment elevations in Newtown Creek. NEED FOR SUPPLEMENTAL BATHYMETRIC SURVEY DATA COLLECTION An initial bathymetric survey was conducted during October and November 2011, as summarized in the Phase 1 Remedial Investigation Interim Data Report (Anchor QEA 2012). Additional hydrographic surveys were determined to be necessary to assess the potential effects of the October 2012 storm Sandy on the Study Area. The purpose of the supplemental bathymetric survey is to: Confirm the bottom topography and water depths for the modeling domain after the recent storm events. Identify areas of potential (or consequential) change in bed elevation for possible additional surface sediment investigation. Information collected during this supplemental survey will be compared to the 2011 bathymetric data and used for various purposes during the Remedial Investigation (RI), such as for revising the conceptual site model, adjusting potential future sampling locations, performing hydraulic analyses and associated computer modeling, and performing contaminant fate and transport modeling. I:\Projects\Newtown_Creek\Deliverables\FSAP\08-FSAP Addendum 4-Bathy\04 Final 2012-12-10\NC_DRAFT_FSAP_Addendum4_2012-12-10.docx
DATA COLLECTION PROCEDURES Caroline Kwan and Nica Klaber Page 2 The bathymetric survey will be conducted in accordance with the methods described in the U.S. Army Corps of Engineers (USACE) Engineer Manual (EM) 1110-2-1003, Hydrographic Surveying, dated January 1, 2002. All of the work performed will be documented, and this documentation will be stored in the project files, as described in the Data Management Plan (DMP; Anchor QEA 2011b). This survey will cover the entire length of the Study Area. To provide greater coverage of the creek bottom, the bathymetric survey will be conducted using a Multi-beam Echo Sounder (MBES) multi-beam survey system. The multi-beam system will be used to the maximum extent possible, including surveying shallow areas during the high tide window (to maximize vessel accessibility). Where used, the MBES system will provide 100-percent coverage of the creek bottom and facilitate the direct comparison of these measurements to those obtained during the fall 2011 single-beam survey. In limited access areas, including nearshore portions of the channel, Dutch Kills, Maspeth Creek, and the heads of side channels, a single-beam survey system will be deployed from a smaller limited-access vessel. For navigation in both the single-beam and multi-beam surveys, the same transect line-file from the 2011 survey will be used with the intent to reoccupy the lines from the 2011 survey when possible. For the single-beam survey, transect spacing will follow the procedures used in 2011 (sufficient to provide data at 10-foot spacing) in identical longitudinal (i.e., shore-parallel) transects approximately 20 feet apart throughout most of the Study Area. These longitudinal transects will be augmented by shore-perpendicular cross-tie transects spaced approximately 200 feet apart. The single-beam transects will follow the 2011 survey transects to the extent practicable and will overlap with the borders of the multi-beam survey areas. Single-beam equipment use and system accuracy will follow the specifications outlined in Section 4.2.2.2 of the FSAP (Anchor QEA 2011a). Multi-beam survey transect spacing will be similar to procedures used in 2011 for the single-beam survey. Transects will be approximately 20 feet apart or at a distance that insures a greater than 100-percent coverage of the bottom. The nadir (vertical beam) will be aimed, when possible, to reoccupy the survey lines from the 2011 single-beam survey. These longitudinal transects will be augmented by shore-perpendicular cross-tie transects spaced
Caroline Kwan and Nica Klaber Page 3 approximately 200 feet apart. The multi-beam depth measurements will be collected using an Odom, Inc., MB-1 echo sounder equipped with a 200-kilohertz (khz) transducer, which forms up to 512 beams across a 120-degree swath of sediment bed. The nadir theoretical accuracy of the MB-1 is approximately 0.1 percent of the water depth with a resolution of 0.033 foot (1 centimeter). Measures will be taken in the field during surveying to achieve this level of accuracy. Digital depths, as well as quantitative backscatter and side scan sonar data, will be recorded to the survey software. All other bathymetric survey assessment activities, including navigation, instrument calibrations, and vertical corrections, will follow the procedures outlined in Section 4.2.2.2 of the FSAP (Anchor QEA 2011a). STANDARD OPERATING PROCEDURES The following standard operating procedures (SOPs) provided in the FSAP (Anchor QEA 2011a), which include data collection forms as applicable, are relevant to this activity: SOP NC-01 Field Records SOP NC-02 Equipment Decontamination DATA PROCESSING, ANALYSIS, AND MANAGEMENT Bathymetry data will be downloaded and saved to the project files. Paper records will be scanned and sent to the Data Management Task Manager. The bathymetric data will be processed by removing outlying data points associated with floating debris or vegetation and converting raw soundings to true elevations. The soundings will be converted to North American Vertical Datum of 1988 (NAVD88) vertical elevations using the procedures identified in the FSAP (Anchor QEA 2011a), including the use of two gauges (time-synchronized pressure transducers) installed within the Study Area. After these adjustments, data will be exported from hydrographic surveying software (HYPACK) in a single American Standard Code for Information Interchange (ASCII) delimited file with fields for northing, easting, elevation, tide correction, and raw depth. Differences between co-located points occupied on perpendicular transects will be tabulated and statistically analyzed to assess and report data quality relative to promulgated USACE Performance Standards. The ASCII file will be used to create gridded surfaces of the sediment bed. A
Caroline Kwan and Nica Klaber Page 4 surface of 1.0-foot square grid cells will be created based on a 95-percent confidence interval analysis of data points. The interpolation method will be selected based on seabed relief and complexity. The surface will be created using the single-beam data and populating it with multi-beam data where available. A contour map of the survey area will be developed from the grid, with the contour interval of 1.0 foot. The resolution of the data will be 1.0-foot square pixels, which are the result of the average of the multi-beam data points with added weight to values closest to the nadir beam using a HYPACK sub-processing routine. Bathymetric survey data will include bathymetry data in electronic format (ASCII X,Y,Z) and bathymetry contours at 1-foot intervals plotted in hardcopy (1 inch = 200 feet scale) and in digital AutoCAD-compatible and ArcView GIS-compatible formats. Survey data will be loaded into Anchor QEA, LLC s (Anchor QEA s) geographic information system- (GIS-) based spatial database and added to the Study Area basemap. REPORTING Upon completion of the surveys and an initial quality review by the Project Quality Assurance (QA) Coordinator or designee, the data will be compiled into summary maps, including a map showing computed elevation differences between the 2011 and 2012 bathymetric survey results, with supporting text. These maps will be included in the Phase 1 RI Data Summary Report, RI Report, and other deliverables, as appropriate. SCHEDULE The bathymetric survey is planned to be conducted in December 2012 to inform subsequent post-sandy surface sediment investigations. The bathymetry data processing and its comparison to the fall 2011 bathymetry measurements will be completed by February 2013. The results of this evaluation will then be used to help inform the selection of appropriate locations for follow-up surface sediment sampling. The schedule will be dependent on weather and field conditions.
REFERENCES Caroline Kwan and Nica Klaber Page 5 Anchor QEA (Anchor QEA, LLC), 2011a. Field Sampling and Analysis Plan. Remedial Investigation/Feasibility Study, Newtown Creek. October 2011. Anchor QEA, 2011b. Data Management Plan. Remedial Investigation/Feasibility Study, Newtown Creek. October 2011. Anchor QEA, 2012. Phase 1 Remedial Investigation Interim Data Report. Remedial Investigation/Feasibility Study, Newtown Creek. June 2012. AC:vs:rrw