B08_5 - CHOH_151201-Reduced - 081632 Final Report-Enviroscan.pdf

1051 Columbia Avenue ● Lancaster, PA 17603 ● 717.396.8922 ● Fax 717.396.8746 ● email@enviroscan.com ● www.enviroscan.com

Final Report Hydrographic Survey - Side Scan Sonar and Bathymetric Data

Big Slackwater II Project – Chesapeake & Ohio Canal National Historic Park Williamsport, MD - Potomac River

Enviroscan Reference Number 081632

Prepared For: Barry Isett & Associates Prepared By: Enviroscan, Inc.

November 8, 2016

1051 Columbia Avenue ● Lancaster, PA 17603 ● 717.396.8922 ● Fax 717.396.8746 ● email@enviroscan.com ● www.enviroscan.com

Mr. Robert J. Cox, P.E.

Barry Isett & Associates 85 South Route 100

Wescosville, PA 18106

RE: Hydrographic Survey - Side Scan Sonar and Bathymetric Data

Big Slackwater II Project – Chesapeake & Ohio Canal National Historic Park

Williamsport, MD - Potomac River

Enviroscan Reference Number 081632

Dear Mr. Cox:

Pursuant to our proposal dated August 19, 2016, Enviroscan, Inc. (“Enviroscan”) has completed hydrographic surveys of the above-referenced site. The purpose of the survey is to identify and map breaks in the C&O Canal towpath that extend into the river, as well as map the river bottom along approximately one mile of the Potomac River. Survey elevations were established with a Topcon RTK-Hyperlite Plus global positioning system (GPS) corrected with the National Geodetic Survey (NGS) Online Positioning User Service (OPUS), and benchmark elevations provided by the client.

The survey was conducted over a two day period ending October 18, using standard and/or routinely accepted practices of the industry and equipment representing the best available technology for multibeam bathymetric and side scan sonar surveys. Enviroscan utilized an

Odom MB1 multibeam fathometer to record profiles, with survey lines spaced at intervals between 15 to 25 feet and spanning the one-mile client-designated areas (Figure 1). Continuous, real-time location control with sub-meter accuracy was maintained using a Hemisphere heading and positioning receiver (10 Hz) global positioning system, with differential corrections applied.

Motion control was recorded with a stand-alone TSS SMD-05 motion sensor. The digital fathometer data and positioning were integrated and stored in ASCII XYZ format, using

HYPACK & HYSWEEP hydrographic navigation software. All data were collected in

Maryland State Plane (feet), NAD-83 coordinates, and corrected for water level variation with the Topcon RTK-Hyperlite Plus GPS base station transmitter/receiver located on the southern shore. A rover transmitter/receiver RTK system was on board the boat, with water level readings taken every ten to fifteen minutes during the survey.

ENVIROSCAN, INC.

Mr. Cox

1051 Columbia Avenue ● Lancaster, PA 17603 ● 717.396.8922 ● Fax 717.396.8746 ● email@enviroscan.com ● www.enviroscan.com

The water elevation on the downstream (320.49 feet) and upstream (320.62 feet) sections of the river remained relatively constant during the bathymetric survey; however, shallow water limited accessibility of the multibeam system in several areas along the shoreline due to rocks and fallen trees. In order to increase data coverage, the multibeam transmitter was tilted 30 degrees for multiple passes.

Enviroscan also performed a high-resolution side scan sonar survey over the survey areas in Figure 1. The purpose of the side scan sonar survey was to provide images of the river bottom by transmitting pulses of high-frequency acoustic energy sub-horizontally from a transducer towed behind a survey boat. The acoustic pulses are reflected by the river floor (as well as by any object or features extending above the river floor) with the intensity of reflections dependent upon the orientation, composition and roughness of the object or feature. As the towfish is towed along a survey profile, the reflections from each pulse are displayed on a computer video monitor in real time, producing an acoustic image of the bottom. In addition to the video, the sonar records are digitally recorded on the internal hard drive for later playback and analysis.

Enviroscan utilized an EdgeTech 4200 Side Scan Sonar System with a trained and experienced operator. The sonar system is capable of simultaneously creating images with two different signal frequencies (300/600 kHz), giving the operator two datasets of the bottom. The sonar system was set to maximize the resolution of the sonar imagery. Location control with sub-meter accuracy was provided by a real-time differential global positioning system (DGPS) to ensure high-accuracy, GIS-compatible mapping.

The survey results are presented on the enclosed drawings as bathymetric contours

(Figures 2.01 through 2.07) and as geo-referenced images of the sonar data (Figures 3.01 through

3.07) for the survey areas. Please note that the shoreline contour is based on the side scan sonar data added to the 2-foot by 2-foot TIN model used for the bathymetric contours, to constrain the

TIN model. Additionally, the geo-referenced images are slightly distorted due to the geo-referencing process – and the inability to perform straight lines in the survey area as a result of currents, and the curved shape of the survey boundary. A sample of the raw images of the side scan sonar with higher resolution and annotations are shown in Figure 4.

Please note that the results of the hydrographic survey were overlain on images based on information from Google Earth images, the RTK and DGPS surveys by Enviroscan, and other open source images.

ENVIROSCAN, INC.

Mr. Cox

1051 Columbia Avenue ● Lancaster, PA 17603 ● 717.396.8922 ● Fax 717.396.8746 ● email@enviroscan.com ● www.enviroscan.com

Limitations

The hydrographic survey described above was completed using standard and/or routinely accepted practices of the industry and equipment representing the best available technology.

Enviroscan does not accept responsibility for survey limitations due to inherent technological limitations or site-specific conditions. However, we make every effort to identify and notify the client of such limitations or conditions.

We appreciate this opportunity to work with you again. If you have any questions, please do not hesitate to contact me.

Sincerely, Enviroscan, Inc.

Charles H. Rhine, M.Sc., P.G.

Senior Geophysics Project Manager

Technical Review By:

Enviroscan, Inc.

Felicia Kegel Bechtel, M.Sc., P.G.

President enc.: Figure 1 – Hydrographic Survey Data Coverage Map

Figures 2.01 to 2.07 – Bathymetric Survey Contour Results

Figures 3.01 to 3.07 – Side Scan Sonar Survey Results

Figure 4 – Side Scan Sonar Raw Data Annotated

Digital Files – Side Scan Sonar Images, XYZ data (2x2 TIN Model)

U p p e r

P o t o m a c

R i v e r

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U p p e r

P t o m v e r

U p p e r

P o t o m v e r

SCALE IN FEET

4000 800

Prepared by:

Project Number

Original Scale

Enviroscan, Inc.

1051 Columbia Avenue

Lancaster, PA 17603

(717) 396-8922 www.enviroscan.com

Revision/Issue

Approved by:Drawn by:

Figure

081632

10/24/16

CHR

1" = 400' FKB

Big Slackwater II

Potomac River

Williamsport, MD

Hydrographic Survey

Data Coverage

October 2016

Survey Date:

10/18/16

General Notes:

The information depicted on this drawing represents survey results on the date surveyed and can only be considered to be indicative of the general conditions existing on that survey date.

Water level elevation established with Topcon RTK-Hyperlite Plus from

North American Vertical Datum 1988 (NAVD88). Horizontal coordinates in

Maryland State Plane (ft), NAD-83 Datum.

Basemap information from Enviroscan DGPS survey and Google Earth image.

S e c t i n

S e c t i

S e c t i

S e c t i

S e c t i

S e c t i

S e c t i

SCALE IN FEET

600 120

Prepared by:

Project Number

Original Scale

Enviroscan, Inc.

1051 Columbia Avenue

Lancaster, PA 17603

(717) 396-8922 www.enviroscan.com

Revision/Issue

Approved by:Drawn by:

Figure

081632

10/24/16

CHR

1" = 60' FKB

Big Slackwater II

Potomac River

Williamsport, MD

2.01

Bathymetric Survey

Contour Results

Section 01

October 2016

Survey Date:

10/18/16

General Notes:

The information depicted on this drawing represents survey results on the date surveyed and can only be considered to be indicative of the general conditions existing on that survey date.

Water level elevation established with Topcon RTK-Hyperlite Plus from

North American Vertical Datum 1988 (NAVD88). Horizontal coordinates in

Maryland State Plane (ft), NAD-83 Datum.

Basemap information from Enviroscan DGPS survey and Google Earth image.

Hydrographic soundings were taken using a survey-grade Odom MB1

Multibeam and real-time differential GPS. Hydrographic contours (1-foot intervals) in feet NAVD88.

600 120

Prepared by:

Project Number

Original Scale

Enviroscan, Inc.

1051 Columbia Avenue

Lancaster, PA 17603

(717) 396-8922 www.enviroscan.com

Revision/Issue

Approved by:Drawn by:

Figure

081632

10/24/16

CHR

1" = 60' FKB

Big Slackwater II

Potomac River

Williamsport, MD

2.02

Bathymetric Survey

Contour Results

Section 02

October 2016

Survey Date:

10/18/16

General Notes:

The information depicted on this drawing represents survey results on the date surveyed and can only be considered to be indicative of the general conditions existing on that survey date.

Water level elevation established with Topcon RTK-Hyperlite Plus from

North American Vertical Datum 1988 (NAVD88). Horizontal coordinates in

Maryland State Plane (ft), NAD-83 Datum.

Basemap information from Enviroscan DGPS survey and Google Earth image.

Hydrographic soundings were taken using a survey-grade Odom MB1

600 120

Prepared by:

Project Number

Original Scale

Enviroscan, Inc.

1051 Columbia Avenue

Lancaster, PA 17603

(717) 396-8922 www.enviroscan.com

Revision/Issue

Approved by:Drawn by:

Figure

081632

10/24/16

CHR

1" = 60' FKB

Big Slackwater II

Potomac River

Williamsport, MD

2.03

Bathymetric Survey

Contour Results

Section 03

October 2016

Survey Date:

10/18/16

General Notes:

The information depicted on this drawing represents survey results on the date surveyed and can only be considered to be indicative of the general conditions existing on that survey date.

Water level elevation established with Topcon RTK-Hyperlite Plus from

North American Vertical Datum 1988 (NAVD88). Horizontal coordinates in

Maryland State Plane (ft), NAD-83 Datum.

Basemap information from Enviroscan DGPS survey and Google Earth image.

Hydrographic soundings were taken using a survey-grade Odom MB1

600 120

Prepared by:

Project Number

Original Scale

Enviroscan, Inc.

1051 Columbia Avenue

Lancaster, PA 17603

(717) 396-8922 www.enviroscan.com

Revision/Issue

Approved by:Drawn by:

Figure

081632

10/24/16

CHR

1" = 60' FKB

Big Slackwater II

Potomac River

Williamsport, MD

2.04

Bathymetric Survey

Contour Results

Section 04

October 2016

Survey Date:

10/18/16

General Notes:

The information depicted on this drawing represents survey results on the date surveyed and can only be considered to be indicative of the general conditions existing on that survey date.

Water level elevation established with Topcon RTK-Hyperlite Plus from

North American Vertical Datum 1988 (NAVD88). Horizontal coordinates in

Maryland State Plane (ft), NAD-83 Datum.

Basemap information from Enviroscan DGPS survey and Google Earth image.

Hydrographic soundings were taken using a survey-grade Odom MB1

600 120

Prepared by:

Project Number

Original Scale

Enviroscan, Inc.

1051 Columbia Avenue

Lancaster, PA 17603

(717) 396-8922 www.enviroscan.com

Revision/Issue

Approved by:Drawn by:

Figure

081632

10/24/16

CHR

1" = 60' FKB

Big Slackwater II

Potomac River

Williamsport, MD

2.05

Bathymetric Survey

Contour Results

Section 05

October 2016

Survey Date:

10/18/16

General Notes:

The information depicted on this drawing represents survey results on the date surveyed and can only be considered to be indicative of the general conditions existing on that survey date.

Water level elevation established with Topcon RTK-Hyperlite Plus from

North American Vertical Datum 1988 (NAVD88). Horizontal coordinates in

Maryland State Plane (ft), NAD-83 Datum.

Basemap information from Enviroscan DGPS survey and Google Earth image.

Hydrographic soundings were taken using a survey-grade Odom MB1

600 120

Prepared by:

Project Number

Original Scale

Enviroscan, Inc.

1051 Columbia Avenue

Lancaster, PA 17603

(717) 396-8922 www.enviroscan.com

Revision/Issue

Approved by:Drawn by:

Figure

081632

10/24/16

CHR

1" = 60' FKB

Big Slackwater II

Potomac River

Williamsport, MD

2.06

Bathymetric Survey

Contour Results

Section 06

October 2016

Survey Date:

10/18/16

General Notes:

The information depicted on this drawing represents survey results on the date surveyed and can only be considered to be indicative of the general conditions existing on that survey date.

Water level elevation established with Topcon RTK-Hyperlite Plus from

North American Vertical Datum 1988 (NAVD88). Horizontal coordinates in

Maryland State Plane (ft), NAD-83 Datum.

Basemap information from Enviroscan DGPS survey and Google Earth image.

Hydrographic soundings were taken using a survey-grade Odom MB1

600 120

Prepared by:

Project Number

Original Scale

Enviroscan, Inc.

1051 Columbia Avenue

Lancaster, PA 17603

(717) 396-8922 www.enviroscan.com

Revision/Issue

Approved by:Drawn by:

Figure

081632

10/24/16

CHR

1" = 60' FKB

Big Slackwater II

Potomac River

Williamsport, MD

2.07

Bathymetric Survey

Contour Results

Section 07

October 2016

Survey Date:

10/18/16

General Notes:

The information depicted on this drawing represents survey results on the date surveyed and can only be considered to be indicative of the general conditions existing on that survey date.

Water level elevation established with Topcon RTK-Hyperlite Plus from

North American Vertical Datum 1988 (NAVD88). Horizontal coordinates in

Maryland State Plane (ft), NAD-83 Datum.

Basemap information from Enviroscan DGPS survey and Google Earth image.

Hydrographic soundings were taken using a survey-grade Odom MB1

600 120

Prepared by:

Project Number

Original Scale

Enviroscan, Inc.

1051 Columbia Avenue

Lancaster, PA 17603

(717) 396-8922 www.enviroscan.com

Revision/Issue

Approved by:Drawn by:

Figure

081632

10/24/16

CHR

1" = 60' FKB

Big Slackwater II

Potomac River

Williamsport, MD

3.01

Side Scan Sonar

Survey Results

Section 01

October 2016

Survey Date:

10/18/16

General Notes:

The information depicted on this drawing represents survey results on the date surveyed and can only be considered to be indicative of the general conditions existing on that survey date.

Water level elevation established with Topcon RTK-Hyperlite Plus from North

American Vertical Datum 1988 (NAVD88). Horizontal coordinates in Maryland

State Plane (ft), NAD-83 Datum.

Basemap information from Enviroscan DGPS survey and Google Earth image.

Side Scan Sonar performed with EdgeTech 4200 Series System, 600 kHz frequency, 45 meter range.

600 120

Prepared by:

Project Number

Original Scale

Enviroscan, Inc.

1051 Columbia Avenue

Lancaster, PA 17603

(717) 396-8922 www.enviroscan.com

Revision/Issue

Approved by:Drawn by:

Figure

081632

10/24/16

CHR

1" = 60' FKB

Big Slackwater II

Potomac River

Williamsport, MD

3.02

Side Scan Sonar

Survey Results

Section 02

October 2016

Survey Date:

10/18/16

General Notes:

The information depicted on this drawing represents survey results on the date surveyed and can only be considered to be indicative of the general conditions existing on that survey date.

Water level elevation established with Topcon RTK-Hyperlite Plus from North American Vertical Datum

1988 (NAVD88). Horizontal coordinates in Maryland State Plane (ft), NAD-83 Datum.

Basemap information from Enviroscan DGPS survey and Google Earth image.

Side Scan Sonar performed with EdgeTech 4200 Series System, 600 kHz frequency, 45 meter range.

600 120

Prepared by:

Project Number

Original Scale

Enviroscan, Inc.

1051 Columbia Avenue

Lancaster, PA 17603

(717) 396-8922 www.enviroscan.com

Revision/Issue

Approved by:Drawn by:

Figure

081632

10/24/16

CHR

1" = 60' FKB

Big Slackwater II

Potomac River

Williamsport, MD

3.03

Side Scan Sonar

Survey Results

Section 03

October 2016

Survey Date:

10/18/16

General Notes:

The information depicted on this drawing represents survey results on the date surveyed and can only be considered to be indicative of the general conditions existing on that survey date.

Water level elevation established with Topcon RTK-Hyperlite Plus from North American Vertical Datum

1988 (NAVD88). Horizontal coordinates in Maryland State Plane (ft), NAD-83 Datum.

600 120

Prepared by:

Project Number

Original Scale

Enviroscan, Inc.

1051 Columbia Avenue

Lancaster, PA 17603

(717) 396-8922 www.enviroscan.com

Revision/Issue

Approved by:Drawn by:

Figure

081632

10/24/16

CHR

1" = 60' FKB

Big Slackwater II

Potomac River

Williamsport, MD

3.04

Side Scan Sonar

Survey Results

Section 04

October 2016

Survey Date:

10/18/16

General Notes:

The information depicted on this drawing represents survey results on the date surveyed and can only be considered to be indicative of the general conditions existing on that survey date.

Water level elevation established with Topcon RTK-Hyperlite Plus from North American Vertical Datum

1988 (NAVD88). Horizontal coordinates in Maryland State Plane (ft), NAD-83 Datum.

600 120

Prepared by:

Project Number

Original Scale

Enviroscan, Inc.

1051 Columbia Avenue

Lancaster, PA 17603

(717) 396-8922 www.enviroscan.com

Revision/Issue

Approved by:Drawn by:

Figure

081632

10/24/16

CHR

1" = 60' FKB

Big Slackwater II

Potomac River

Williamsport, MD

3.05

Side Scan Sonar

Survey Results

Section 05

October 2016

Survey Date:

10/18/16

General Notes:

The information depicted on this drawing represents survey results on the date surveyed and can only be considered to be indicative of the general conditions existing on that survey date.

Water level elevation established with Topcon RTK-Hyperlite Plus from North American Vertical Datum

1988 (NAVD88). Horizontal coordinates in Maryland State Plane (ft), NAD-83 Datum.

600 120

Prepared by:

Project Number

Original Scale

Enviroscan, Inc.

1051 Columbia Avenue

Lancaster, PA 17603

(717) 396-8922 www.enviroscan.com

Revision/Issue

Approved by:Drawn by:

Figure

081632

10/24/16

CHR

1" = 60' FKB

Big Slackwater II

Potomac River

Williamsport, MD

3.06

Side Scan Sonar

Survey Results

Section 06

October 2016

Survey Date:

10/18/16

General Notes:

The information depicted on this drawing represents survey results on the date surveyed and can only be considered to be indicative of the general conditions existing on that survey date.

Water level elevation established with Topcon RTK-Hyperlite Plus from North American Vertical Datum

1988 (NAVD88). Horizontal coordinates in Maryland State Plane (ft), NAD-83 Datum.

600 120

Prepared by:

Project Number

Original Scale

Enviroscan, Inc.

1051 Columbia Avenue

Lancaster, PA 17603

(717) 396-8922 www.enviroscan.com

Revision/Issue

Approved by:Drawn by:

Figure

081632

10/24/16

CHR

1" = 60' FKB

Big Slackwater II

Potomac River

Williamsport, MD

3.07

Side Scan Sonar

Survey Results

Section 07

October 2016

Survey Date:

10/18/16

General Notes:

The information depicted on this drawing represents survey results on the date surveyed and can only be considered to be indicative of the general conditions existing on that survey date.

Water level elevation established with Topcon RTK-Hyperlite Plus from North

American Vertical Datum 1988 (NAVD88). Horizontal coordinates in Maryland

State Plane (ft), NAD-83 Datum.

Basemap information from Enviroscan DGPS survey and Google Earth image.

Side Scan Sonar performed with EdgeTech 4200 Series System, 600 kHz frequency, 45 meter range.

Prepared by:

Project Number

Original Scale

Enviroscan, Inc.

1051 Columbia Avenue

Lancaster, PA 17603

(717) 396-8922 www.enviroscan.com

Revision/Issue

Approved by:Drawn by:

Figure

081632

10/24/16

CHR

NA FKB

Big Slackwater II

Potomac River

Williamsport, MD

4.00

Side Scan Sonar

Raw Data Annotated

October 2016

Survey Date:

10/18/16

General Notes:

The information depicted on this drawing represents survey results on the date surveyed and can only be considered to be indicative of the general conditions existing on that survey date.

Side Scan Sonar performed with EdgeTech 4200 Series System, 600 kHz frequency, 45 meter range.

Raw data images shown in time (pings per second) without slant correction or geo-referenced. Approximate distance shown based on range settings and boat speed. Vertical ≠ Horizontal

Raw data images shown in time (pings per second) without slant correction or geo-referenced. Approximate distance shown based on range settings and boat speed. Vertical ≠ Horizontal