International Dredging Review

International Dredging Review

In early December 2010 Ross Laboratories delivered three turnkey five-channel sweep survey boats with trailers to the U.S. Army Corps of Engineers Mobile District. The boats will be used by the Tuscaloosa Area Office in its mission to survey and map 700 miles of the Black Warrior Tombigbee and Alabama River Systems.

The boats were placed into working status in mid-January 2011.

Ross installed the Dolphin Mini Sweep™ survey systems on SeaArk custom-designed 24-foot cathedral hull work boats.
The boats are: Corps Survey Vessel 6208 operated by surveyor David Files; Corps Survey Vessel 6212 operated by surveyor John W. Andrews; and Corps Survey Vessel 6215 operated by surveyor Lance Holloway. The operators work alone trailering the boats to the project location and handling launch surveying and take-out as solo operations.

The new vessels replace three sweep survey boats that have been in operation for over 15 years and will work along with the 65-foot E.B. Wallace a 12-channel sweep system that Tuscaloosa survey crews have operated since 1990 conducting channel maintenance and condition surveys with in the district.

The new small boat sweep vessels were built using funds from the American Recovery and Reinvestment Act (ARRA).

“The specifications…were quickly put together once I was notified that we had the ARRA funding for replacement of our three aging survey boats” said Mark Goddard who manages the technical team of the of the BWT/Alabama Coosa Project Management Office’s Area Navigation Unit. “I was able to prepare the wording for the survey system portion using the original sweep survey system specification from back in the early 90s with some major tweaks on improvements and updates on new technology. Scott Beams prepared the marine vessel construction portion of the specifications which was subcontracted by Jim Ross to SeaArk Marine” he said.

Delegations from the Tuscaloosa office and Ross Labs visited SeaArk on July 13 and 14 2010 for tests of one of the boats. Among this group were Scott Beams mechanical engineer from the Mobile District office and floating plant specialist for the Operations Division Mark Goddard and David Files from Tuscaloosa and Jim Ross and Dean Graddon from Ross Labs.

Installing the Systems

The three boats were delivered to the Ross offices in Seattle in August and Ross technicians began immediately to install the survey systems and transducer booms.

The Mini-Sweep system is ideal for use on small trailerable vessels which concentrate on surveying at depths from two to 20 feet deep getting coverage as good as or better than multibeam systems. This allows surveying in small ponds or backwaters where it would be difficult to take a larger boat.

The 10-foot booms provide a 25-foot overall sweep width. They are stored in recessed areas in the hull leaving the deck clear at all times and are hydraulically deployed from the helm. This feature is an improvement on the previous survey boats which required the operator to go on deck and hand-crank the booms into place.

Electronics are stowed in a custom-built work cabinet containing the Model 4810 five-channel depth sounding system Panasonic Toughbook™ data collection computer and a Trimble SPS461 RTK GPS system. Hypack™ software is used for data collection and processing. RTK (real-time kinematic) service is provided from a local vendor’s network. RTK positional data is received using Intuicom brand RTK bridges and cellular network service.

The three operators and Mark Goddard visited Ross Laboratories in early November for sea trials and training on Lake Union in front of the Ross offices. They all boarded one of the boats and took turns at the helm familiarizing themselves with the new features of the systems.

The boats were in their new home in Alabama in early December.

One of the Oldest Field Units

The BWT/Ala Coosa Project Management Office Tusscaloosa Navigation Unit in Tuscaloosa Alabama is one of the oldest field offices of the Mobile District Mark Goddard told IDR. Its survey fleet provides support for maintenance dredging and associated surveying required for Operation & Maintenance of more than 700 miles of authorized navigation channel of the Black Warrior-Tombigbee and Alabama-Coosa River Systems. Figure 1 depicts the Tuscaloosa Area Office mission area.

The project area ranges from the confluence of the Alabama and Tombigbee Rivers 45 miles north of Mobile up the Tombigbee and Warrior Rivers to near Birmingham Alabama and from the confluence of the Tombigbee River up the Alabama River to near Montgomery Alabama. Project authorization provides a nine-foot by 200-foot navigation channel with a total of nine locks and dams on both systems. Responsibilities include providing accurate condition and detailed dredging surveys for maintenance dredging activities at both the field and district levels.

The Tuscaloosa office conducts hydrographic surveys
annually along the 400 miles of the Black Warrior-Tombigbee Rivers and 300 miles of the Alabama River to determine project conditions and to analyze dredging needs. On average more than 300 individual detailed surveys are made by the unit’s four survey vessels. Mapping of the project’s traditional shoaling areas is done throughout the year in individual survey areas averaging 3500 feet in length. These surveys are used for detailed dredging analysis needs and are usually conducted in the April-through-September time frame or after the spring floods have ended and during actual dredging operations.

Additional mapping or historic mapping of the remaining long stretches of river or bank-to-bank mapping is performed regularly by all four boats in areas that cover five to 10 mile stretches at a time using longitudinal sweeps from waters-edge to waters-edge to provide total mapping coverage of the entire 700 mile of rivers.

The three new boats along with the 60-foot E.B. Wallace comprise the Navigation Unit survey fleet.

Each of the new vessels provides a twenty-five-foot-wide sweep coverage of the bottom using five transducers mounted on 10-foot fully hydraulic booms and can provide survey data in shallower areas than the E.B. Wallace.

The small boats are transportable and will be used either to systematically cover a designated river portion or to respond to specific complaints of the river system users. The small boats have the flexibility to interchange when one of the other boats or systems are down as the systems are identical.

The E.B. Wallace uses a Ross Dolphin Mini Sweep system with two 30-foot hydraulically operated retractable booms. Each boom contains five spring-loaded strut transducers spaced six feet apart with two additional transducers mounted in the hull for a total of 12 transducers. The sweep arms provide a complete 70-foot swath of the river bottom at depths of 17 feet.

Navigation Unit Organization

The Navigation Unit which operates the three new boats is part of the the BWT/Alabama Coosa Project Management Office a multi-purpose field project of the Mobile District.

Projects managed by this office include hydropower navigation and recreation functions on the Black Warrior-Tombigbee and Alabama-Coosa river systems with headquarters in Tuscaloosa Alabama.

The Navigation Unit is divided into two units: the technical team and the inspection team. The inspection team provides contract field inspection for construction and dredging projects and the technical team provides survey and mapping functions in support of navigation and dredging. The navigation unit consists of leader Fred Horn who is chief of the Navigation Unit the E.B. Wallace survey vessel with two employees the inspection team with two construction representatives (dredge and construction inspectors) the technical team consisting of Manager Mark Goddard supervisory engineer technician; the three small boat surveyors who perform land surveys as well as one-person small-boat hydrographic surveys; a cartographer a GIS specialist and one cartographic/engineering technician who processes the survey data into finished maps.

The editor thanks Mark Goddard David Files and John Andrews for making a special field trip to obtain the photos of the boat launching procedure at Old Lock 1. Thanks also to Mark Goddard and Jim Ross for being available to answer many many questions during the writing of this article.