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<br />/ <br /> <br />Gerd Marggraff (510-828-1992) <br /> <br />Marina Dredging Speech for City Council <br /> <br />3-20-07 <br /> <br />My name is Gerd Marggraff. I reside at 13055 Neptune Drive. I have been in the <br />maritime and building industry for over 20 years. I have operated boat yards, <br />been in the marine charter industry, sailed around the world with my wife, and <br />have owned a small marina overseas. <br /> <br />The main problem, I'd like to address is an idea to make the dredging more <br />affordable. The dredging systems I would like to introduce you to have been used <br />in Europe for over 50 years and are now operated in a National marine park that <br />stretches over 3 countries on the North Sea. From an environmental view, this <br />park has some highly sensitive areas. All three systems I will mention are <br />designed on a high volume and low pressure sediment agitating system...very <br />unlike the cutting head dredges used by the Corps of Engineers. These systems <br />are a product of the ingenuity of marine engineers of the Netherlands and <br />Germany. All these systems agitate the sediment and allow the current to carry <br />away. Because the San Leandro channel has been previously dredged, the <br />unwanted sediment will be relatively soft, easy to agitate, and environmentally <br />acceptable as we are not disturbing deeper sediment layers. The three systems <br />vary in size, cost, & efficiency: A short description is induded in this paper for <br />reference. <br /> <br />System 1: The oldest existing system uses a propeller shaft system that can be <br />. hydraulically or mechanically adjusted in angle to sediment bed. If this angle is <br />steep, the maximum thrust goes into the sediment, agitates it, and saturates the <br />water with sediment. Timing the tide and currents correctly, this sediment will be <br />carried away. As simple this system might sound, it is still in use for shallow side <br />arms and harbor basins in the North Sea that require a maximum depth of <br />approximately 8 feet. Since it is very cheap to operate, with a small (50ft) <br />pontoon boat, driven by 150-200 hp engines, smaller harbors often use this <br />technology. I have personally, built one of these systems for a private yacht club <br />for less than $50,000. This dredge, built quite a while ago, is still operating today. <br /> <br />-r- <br />