Many school natatoriums are showing their age. Even those constructed with state-of-the-art materials 20 to 30 years ago are exhibiting the corrosive effects associated with the high humidity of pool environments. Heating, ventilation, humidity control, filtration, water treatment, plumbing and lighting systems have suffered from wear and tear. These systems may not meet health-department standards or satisfy campus needs.
Schools and universities use their pools for more activities than ever before. Community use has grown over the years, and special groups of users, including disabled persons, senior citizens and children in on-campus daycare facilities, also are getting into the swim.
Therefore, re-evaluating a pool program is important when planning a facility upgrade. It will help administrators identify the physical changes needed to accommodate new programs. The evaluation should consider the school's need to provide physical education; competition (including facilities for spectators and visiting teams); recreation; life-saving and water-safety instruction; synchronized swimming; water aerobics; sessions for disabled users; seniors; young children and other groups; and special activities.
The big three
Three critical engineering issues in older pools are recirculation, filtration and dehumidification. The pool recirculation system typically requires the greatest degree of modernization. Almost every applicable code requires that a pool be able to recirculate 100 percent of the pool's water through the main drains at the bottom of the pool and 100 percent from the top — that is, from the surrounding gutter. Unfortunately, many old pools take all the water for recirculation from the main drains and send the water that overflows into the gutter straight to the wastewater system.
New systems are designed so that under normal operation, 20 percent of the water to be recirculated is taken from the main drains and 80 percent from top, promoting a skimming action that helps keep pool water clean. Upgrading a pool to accomplish this usually requires a new gutter and a surge tank or balance tank to collect the overflow. If the budget does not allow for a new gutter, it may be possible to redirect overflow from the wastewater system to the surge tank or balance tank, but it will still be difficult to recirculate 100 percent of the water from the top, and a code variance will be required. Most codes also require water inlets to be adjustable both for direction and quantity, so these may have to be replaced.
Because of the corrosive action of chemically treated water, the recirculation system also is likely to need a piping retrofit — from cement-lined steel piping or ferrous material to CPVC plastic or PVC, depending on local codes. Pool volume dictates the capacity of recirculation pumps and the filtration rate.
That brings us to filtration. Most states require 100 percent water recirculation every six hours for recreation, competition and diving pools; a higher standard than what was typically in place 30 years ago. Standards are even higher for special circumstances. For a wading pool used by children under 6 — a possibility if there is an on-campus daycare program — the filtration system should produce a complete water change every two hours. Thus, schools must assess their pools' filtration rates to see if they need to be improved.
As for the filter itself, most older pools use diatomaceous earth filters, which are effective but require higher levels of maintenance. In some locations, they are treated as hazardous waste and require special disposal methods. As a result, many owners retrofit with high-rate sand filters if local regulations permit.
Once pool water is filtered, it is typically heated to 80 to 82°F. Water heaters often remain in working condition after 20 years, but pumps may require replacement. As for chemical disinfection, improved environmental standards require chemical tanks and piping to be double-walled to contain leaks. An emergency shower and eyewash also should be available in the pool equipment room.