Before any dredg-ing occurs, Pre-placement Condition Surveys are required. Stationing is identified along the baseline within the project area on plans prepared by the Philadelphia District. The existing control monuments are typically set at angles in a survey baseline, which runs generally parallel to the shoreline. A base station receiver is set on one control point and others are surveyed via RTK to verify their integrity before any profile surveying begins. In most cases, the Corps of Engineers has existing control monumentation. In many other ways, these projects are no different from any other. Relying on tide charts instead of satellite ephemerides is fundamental to successfully surveying each profile line. The surveying of beachfill certainly does not have the same accuracy requirements as staking out steel columns, but these projects have their own set of obstacles to confront. Army Corps of Engineers, Philadelphia District. Both of these projects are under the jurisdiction and direction of the U.S. Recently, McKim & Creed (Wilmington, DE), HRG (Herbert, Rowland & Grubic, Inc., Harrisburg, PA), and T3 Global Strategies (Bridgeville, PA) teamed together to provide these surveying services to Weeks Marine on dredging projects in Cape May and Brigantine, New Jersey. The level of effort on these projects, from the surveyor's perspective, has been greatly reduced by the use of RTK for both on-shore land surveying and off-shore hydrographic surveying. This is essential in determining if design volumes have been achieved by the dredging efforts. Profiles are necessary to check before-dredge, but more importantly to verify after-dredge conditions. One such example is the surveying of shoreline profiles to support dredging on beach renourishment projects. While the use of GPS has become commonplace for aerial ground control, GIS surveys, construction staking, etc., we also look for new and unique projects that could not otherwise be accomplished without GPS. All of these advancements have impacted all of us in a generally positive way, thus reducing levels of effort and increasing productivity. While the first EDM mounted onto a theodolite has emerged into robotic, reflectorless total stations, single frequency GPS and static networks have emerged into cellular RTK and Virtual Reference Systems. After nearly 20 years of GPS integration into the field of surveying, it seems that there are no boundaries on the growth of this technology.
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