You surely have heard of "dredging the river" in conjunction with trying to find a body, right? Well, spot dredging is similar to that, with the exception that it has another purpose. There are also reasons why spot dredging may be used instead of dredging an entire body of water. To help you understand the role of spot dredging in construction, here is more on the topic.
Spot Dredging Pulls up Bottom Sludge
Spot dredging pulls up bottom sludge. A company may request that bottom sludge in a waterway is pulled up for the purpose of eliminating PCBs and other toxins in the bed of the waterway, or that the spot dredging is used to create an underwater embankment onto/into which pylons can be installed to support a bridge or other structure. By spot dredging, only one small area or several separate small areas are excavated underwater, which is often less harmful to the underwater life and environment than dredging an entire waterway.
Why Spot Dredging Is Used
Spot dredging is localized. It limits the area to be dredged to a very well-defined spot. Most of the rest of the waterway is left undisturbed, which means that fish can spawn in peace, and plant life in the waterway is relatively undisturbed. Unwanted substances and invasive species clinging to these areas are promptly removed and destroyed. Embankments are built to prevent erosion and/or prevent a waterway from changing its course in the event of a flood. Lastly, spot dredging aids in construction projects in very notable ways.
How Spot Dredging Is Related to Construction
Spot dredging is used in construction when something like a bridge is being constructed. In rare instances, actual islands are created during dredging with the intent to build a big enough island structure to support dam operations and remove enough riverbed soil so that the dams can be constructed. In creating and wedging dams in place, everything from water control to electrical power is possible.
When an operations island for a dam system is constructed, the only other purpose for spot dredging is building a bridge. Pylons of soil are constructed under the soon-to-be-available bridge. On those pylons, the "feet" of the bridge are constructed, using concrete to steady the dredged soil and construct the bases of the "feet." From there, the construction contractor and his/her crew are able to build the rest of the bridge.