A shell pump is a simple type of pumping apparatus that removes wet sand or mud from an area that is going to be excavated or drilled. A shell pump is essentially a hollow cylinder that has a ball or one-way valve at the bottom of it. The cylinder exists so the shell pump can open wide to suck up large or thick materials, but close completely when shut off so the material does not back flow into the area that has just been pumped.
Shell pumps are often used to pump out wetlands or areas that are soggy prior to construction. They may also be used to remove wet sand or mud from the bottom of the sea floor. This is done in preparation for undersea archaeological digs or oil or natural gas drilling. Shell pumps are not expensive to operate, but since they are generally rather large pieces of capital equipment intended to do large jobs, they are typically rented out or hired out by the job if they are necessary, although they may be owned by those who have a repeat need for the items.
Shell pumps are very simple to maintain, create, and clean, which makes them popular for areas such as hurricane hit regions where basements and other areas may be filled with thick mud and debris. A shell pump provides a good option where tools and electrical power may not be readily available to fix or maintain the pumps if they begin to gunk up or otherwise malfunction. Shell pumps may also be used in pumping out areas like the dikes of the Netherlands, where they reclaim farmland by building a dam and then pumping out the mud and sand and other debris to replace it with fertile soil.
Shell pumps may be mounted on trucks or, in larger cases, on ships or trawlers that have the capacity to carry away the mud and sand. They may also be used in smaller form in order to clean out small jobs. In some cases, shell pumps are used for recovering sunken ships or lost treasure under the ocean, where they are used like gigantic wet dry vacuum cleaners to suck up portions of the sea floor that have shifted over time to reveal the debris from a shipwreck or other maritime disaster.