Thompson Pump Aids In The Salvation Of The Cape Hatteras Lighthouse
The original Cape Hatteras Lighthouse was erected in 1794. In 1870 erosion danger demanded a new lighthouse that was built 600 feet north of the original landmark. In 1989, The National Park Service determined that the Cape Hatteras Lighthouse was in danger once again. Nearly ten years later, congress approved the decision to move the current structure as the Atlantic Ocean crept to within 100 feet of the structure. The plan was to move the lighthouse approximately one-half mile north to remove it from the eroding shoreline.
Thompson Pump was called upon in January 1999 by Crum Construction, a subcontractor for the project hired by general contractor International Chimeny Corporation of Buffalo, NY. A Thompson Pump Engineering Team consisting of Dale Conway, Majid Tavakoli and John Jeffries designed a cost-effective dewatering plan to aid in moving the lighthouse. Their design required the utilization of wellpoint dewatering systems around the existing structures’ location in addition to their future location. These shallow well dewatering systems were first installed around the lighthouse and the structures housing the two keepers’ quarters. The soil conditions made installing the wellpoints a difficult procedure because the presence of non-permeable peat hinders the dewatering process. Special care needed to be taken to ensure that the wellpoints were in position beyond the peat later to properly dewater the area. The base of the lighthouse consisted of submerged pine timber. Because the salt water preserved the timber, it was essential that it remain submerged so it would not corrode in the open air, thus weakening the foundation on which the lighthouse was standing. The difficult task of effectively dewatering the area while keeping the timber base submerged was accomplished by running the pumps for six-hour intervals. Once the quarters were excavated the system was relocated to the new site. The second wellpoint system was then installed to allow for the construction of the new lighthouse foundation.
These systems required the usage of over 1,200 linear feet of 8” Thompson Header Pipe and 235 wellpoints to handle the necessary dewatering. A total of four Thompson Rotary Wellpoint Pumps operated the system; two 12” models and two 8” models. During the early portions of the job, in excess of 540,000 gallons of water were removed per day. As the job progressed and the water was controlled, the volume of water decreased. Upon completion of the keeper’s quarters’ relocation, part of the system was removed. However, nearly 800 feet of header and two pumps remained on the project. The dewatering system remained in place and continued to run until the lighthouse reached its new location and the cribbing was removed.
The equipment had been on the job since the first of February and had run virtually trouble free allowing the project to remain on schedule. The nearly 3,000 foot move of the lighthouse began on May 17, 1999 and was completed in mid-July.
Bill Thompson, President of Thompson Pump stated, “We are honored to have been associated with this excellent construction team and the representatives of the National Park Service, International Chimney and Crum Construction. It is very gratifying to be involved on a project of such historical and cultural significance.”