Thompson Pump Overcomes Challenges in Installing Wellpoint System
In construction, a wellpoint system is ideally used to lower the water table to make the ground denser to support a building or structure, and to allow for excavation for any underground facilities or utilities. Normally, the wellpoint system is installed and operational before any construction can begin, and continues to operate during the excavation and construction of any underground facilities.
One of the most important components of a wellpoint system is the riser pipe. A riser pipe is a rigid pipe made of steel or PVC that connects to the top of a wellpoint to allow the wellpoint to reach the certain depth required to effectively lower the water table. A riser pipe may reach lengths of up to 25-feet. A clear space overhead is necessary to allow for clearance of the riser pipe so it can be raised vertically and installed into the ground.
Sometimes, problems arise or the best conditions are not available. A need to overcome obstacles, and a thinking-out-of-the-box point-of-view may be needed to rise above the situation.
Such was the case in a construction project for a luxurious beachfront hotel in Myrtle Beach, SC. The contractor was having difficulties on this particular project from many different areas, causing construction to be extremely far behind schedule. The contractor knew that in order to get back on schedule, much less be ahead of schedule, certain phases of the construction would have to be addressed at a later time. One such requirement was that the footers of the hotel structure required an epoxy waterproofing due to the beachfront location. The footers were located under the ground level in what eventually would become the hotel storage area that included pool access for guests. The work had progressed and 4 of the 12-stories of the hotel were already completed before the contractor was able to allot the time and the resources to waterproof the footers.
When it was time to address the waterproofing, crews faced even more difficulties. In order to gain access to the buried footers, the beach sand would have to be removed. In spite many attempts to dig up the area around the footers and to use different makeshift barriers, the sand and water would seep back into the holes and bury the footers again or make them unsuitable for waterproofing.
The contractor was very familiar with Thompson Pump, and in fact owned various Thompson Pump accessories, and had worked on other projects with Thompson Pump in the past. Thompson Pump proved themselves experts in overcoming difficult obstacles incurred when dewatering other hotel and condominium construction sites in the Myrtle Beach area, and across the nation. Immediately, the contractor contacted Thompson Pump’s Charleston, South Carolina branch for their assistance.
After visiting the jobsite, Thompson Pump representatives found that in order to waterproof the footers properly, the water table needed to be lowered 5-feet below its current depth. Thompson Pump also found that since the structure was already built, they had the storage area ceiling to contend with, which was about 8-feet high. The length of the wellpoint risers, with the wellpoints attached, would have to be 12 - 14-feet long in order to lower the water table enough to waterproof the footers. Using normal wellpoint installation methods would prove impossible due to the 8’ height of the ceiling.
Thompson Pump supplied two 12-inch Rotary Wellpoint Pumps with 240-feet of header pipe and about 100 wellpoints with enough riser pipe to extend each of the wellpoints to their desired depth. The Thompson Pump Rotary Wellpoint Pump is “the original” rotary wellpoint pump, having been invented by Thompson Pump’s founder, George A. Thompson, and is trusted by contractors worldwide. Capable of a maximum capacity of 3,000 gallons per minute, and 400-cfm of air handling, the Thompson Rotary Wellpoint Pump is the pump of choice on any wellpoint application.
In order to deal with the ceiling height limitations, Thompson provided a specialized cutting tool. The cutter acted much like a lawn trimmer or weed wacker. Two pieces of 1½-inch steel using rotating cutting teeth attached to one end of a steel pipe. As pressurized water is introduced into the top opening of the pipe, the cutting teeth rotate on the bearing and cut into the ground. The cutter pre-bored the holes that allowed the wellpoints and riser pipe to be installed without concern for the ceiling restrictions.
Thompson Pump supplied a 6-inch Clear-Liquid High Pressure Pump in order to provide pressurized water as high as 173-psi to power the cutting tool.
Once the holes were bored, the 12-14” PVC wellpoint and riser pipe assemblies were then installed. Because the ceiling height was 8’, and the wellpoint and riser pipe assemblies were from 12’-14’, the PVC, being pliable, had to be bent and maneuvered into the hole by hand. After all the wellpoints were properly installed in the ground, the rest of the wellpoint system could be installed. Header pipe with header valve assemblies, header couplings, swing hose and various elbows and caps comprised the system and were installed around the inside walls of the structure.
Although the application was a prime example of doing things the hard way, the water table was lowered, the beach sand could finally be removed and the footers were successfully waterproofed – bringing construction back to schedule.