By Tim Long
In our previous articles on pool construction we have discussed design, required city permits, excavation and steel reinforcement. We are almost ready for shooting the pool shell. However we most consider that some tasks required in the construction of must be at least partially performed before the pool shell is built, namely the plumbing and electrical work. Both of these tasks will not be fully complete until much later in construction process. Yet where either of these tasks will penetrate through the pool wall, the must be laid before the shell is installed.
The easiest explanation of the plumbing is built on the understanding that the water in the pool completes a circuit, which is known as the hydraulic system. It must first be pulled from the pool, filtered, heated if desired, perhaps even treated chemically, then returned to the pool. This process begins with the water being extracted through the skimmers and the main drains. The skimmers which mounted at the water level are designed to catch leaves and other floating debris which is collected in a basket. It is advisable to have more than one skimmer installed in your pool, particularly in environments with lots of foliage or on larger pools. Better pool designers and builders will insist on at least two skimmers on every pool and increase their number as the situation warrants. The exception to this is on pool designed with either a “vanishing edge” or a “raised perimeter overflow”. The vanishing edge pools have at least a portion, usually an entire side, where the water spills over the wall of a pool and into a trough or catch basin. Raised perimeter overflows are pools partially lifted out of the ground. Here the water spills over the entire perimeter of the pool, usually into a hidden trough which surrounds the pool. Both of these types of pools offer dramatic visual effects and usually have no skimmer. This is because the trough or catch basin often acts like a huge skimmer. These pools stay remarkably clean!
The main drain, which is a misnomer, is currently the source of much saftey discussion. It really should not be called a drain since it does not allow you to drain your pool. Neither should it be considered the main source of water for your pool equipment, in that the equipment should only rarely receive all its water from these drains. Technically these devices are referred to as “suction outlets”. It is vitally important that the hydraulic system of any pool be designed with care. Recently congress passed the Virginia Graeme Baker Pool and Spa Safety Act. This law purpose is to reduce the danger of these outlets by requiring outlet covers pass strengant testing requirements and that outlet placement meet certain standards to reduce the likely hood of someone becoming entraped by these outlets. However there is no requirement that a pool actually have these suction outlets. Constructing a pool without them altogether will more than just lower the possiblility of a suction entrapment, but will compeletly eliminate it! The photo pictures placement of these suction outlets as currently required. If you look carefully you will notice that the installation has altered the steel layout which will have to be corrected before the shell is shot.
After the water has been filtered and otherwise treated, it is returned to the pool via the returns fittings attached to plumbin which extends through the pool shell wall. Prior to the shell construction, the plumbing for these returns must be placed and secured into position so that they can not be moved as the shell is placed.
A similar process must be completed for the electrical work. Codes require that the steel be tied electrically to the electrical system through a bond, which is a wire that runs from the pool equipment and to the pool structure and is tied in several places directly to the stell reinforcement of the pool. Since most pools are constructed with an underwater light the conduit for the light must also be installed at this time.
Later the more plumbing and electrical work will have to be completed. But with the inital work complete, specfically where there work extends through the pool wall, the pool is now ready for the next step, the shooting of the pool shell!
To review a FAQ (frequently asked questions) Report prepared by the Health Department of the State of Texas regarding the Virginia Graema Baker Pool and Spa Safety Act – Click Here!
To read the previous article in this series, click here: Steel Reinforcement, It’s the Pool’s Skeleton!