Whether in New York, Los Angeles, Miami, San Francisco, Dallas or the Hamptons, any water source that people interact with needs to be treated to keep them safe.
Simple Logic
Health codes require wading pools, swimming pools and spas all require filtration and sanitization. It is common sense that any water that people touch, run through, or play in - also be treated. Yet, health laws in all states do not require water treatment.
Filtration and Sanitization
To protect the public safety, fountains where people touch the water, all need to have the water kept safe.
Fountains where children run through the water are the worst offenders. These fountains, whether designed for this purpose or not, need to assume public contact with the water.
Paolo Benedetti, SWD
Aquatic Artist, Watershape Consultant, Expert Witness, International Construction Management
Contact the author at: info@aquatictechnology.com or 408-776-8220
"Creating water as art."™
Aquatic Technology Pool and Spa©
©www.aquatictechnology.com
All rights reserved.
http://no.clavinuk.com
Sunday, August 31, 2014
Tuesday, August 26, 2014
Swimming Pool Water Loss - Perimeter Overflow
As a Swimming Pool Construction Defects Expert Witness, I recently consulted on a newly completed perimeter overflow swimming pool in Florida.
The owners had a number of concerns regarding their new pool. Their issues related to the operating levels of the surge tank and suspected water loss.
The bottom line - The hydraulics of this project were not planned or executed properly.
Surge Tank Sizing
The surge tank was too small and was installed at the wrong elevation relative to the pool. The surge tank was also not sized sufficiently to accommodate the draw down for the solar system.
Due to the tank being under sized, when the solar panels filled, the tank's operating level dropped and the fill line sensor activated. The tank would then eventually return to it's proper operating level with make-up water from the water meter.
However, when the systems shut off, the water in the solar panels would drain down into the tank. Now the tank is too full.
As the level in the tank rose above the overflow line, it backed up into the gravity drain line and out of the perimeter overflow slot. The water collects on the pool deck the until the tank's overflow line can drain water to waste. Repeat this process everyday, and it amounts to over a hundred thousand gallons of wasted water.
Not to mention the wasted money for the water, energy to heat and filter that water and the chemicals to treat it.
Bather Displacement
When bathers swim in the pool, their body mass and movements displace water into the surge tank.
The relative shallowness of the surge tank, cause the tank's water level to rise above the over flow line. Valuable water is needlessly discharged into the storm drain, just from swimming in the pool.
Proper Calculations
There is no such thing as a surge tank that is too large.
Proper sizing of a surge tank needs to provide freeboard (excess empty tank volume) below the over flow line, so that the pool can actually be swam in without discharging water into the storm drains. Imagine, people actually swimming in a pool... what a novel idea!
The surge tank also needs to have sufficient volume of water in storage, to allow for the draw down effect that occurs when the system first starts up each day. Since the pumps draw from the tank, the level in the tank will continue to drop until that water reaches the pool, fills the gutter and gravity drains back to the surge tank. This volume of water is called water in transit.
Additionally, an amount of water must be stored for other demands that will be placed upon the surge tank. If fountains, solar panels or water feature pumps will also draw from the same surge tank, then a volume of water in transit must also be provided for these features.
Finally, a protective level of water must be maintained in the tank to prevent any of the pumps from running dry. This is called the minimum operating level (MOL). This level is usually 12 inches, but it may need to be deeper depending upon the size of the pumps. High horsepower pumps can easily vortex in 12 inches of water.
The sensor for the auto-fill will be set just above the MOL. This is to ensure that the water level in the tank never drops below this safe level.
Surge Tank Elevation
The slope of the gravity drain lines and the distance of the surge tank from the pool, will determine the entry point of the gravity drain line into the surge tank. The further away from the pool the surge tank is place, the deeper below grade it will enter the tank. Obviously this also increases the cost of a site fabricated tank. Manways, ladders or increased tank heights all contribute to additional costs.
The maximum operating volume of the tank is the tank's volume that exists below the entry point of this gravity drain line. So if the gravity drain line penetrates the surge tank too low, the tank capacity is greatly diminished.
The solution? Build the surge tank deeper below the entry point of the gravity drain line.
Planning
Of course getting all of these volumes and elevations correct requires a lot of planning. Perimeter overflow pools cannot be designed without creating cross-sectional drawings.
The locations of the various pipes (overflow and fill lines, sensor stand pipes, suction drains, vacuum port) and the entry point of the gravity drain line must all be carefully calculated.
Always a Solution
Sometimes the surge tank needs to be relocated closer to the pool, in order to raise the entry point of the gravity drain line.
When space is limited, our firm builds the surge tank adjacent to the pool. This allows for sharing a common wall and reducing construction costs.
If the tank size and depth is constrained by project parameters, then we may specify balancing valves. Of course balancing valves only work if the tank can be built slightly above the pool, say in a nearby planter or in an elevated portion of the patio.
Knowledge and Planning... FOR SALE HERE.
Paolo Benedetti, Pool Designer, Aquatic Artist, Watershape Consultant, Expert Witness, International Construction Management
Contact the author at: info@aquatictechnology.com or 408-776-8220 "Creating water as art."™
Aquatic Technology Pool and Spa© ©www.aquatictechnology.com
All rights reserved.
clavinuk.com
The owners had a number of concerns regarding their new pool. Their issues related to the operating levels of the surge tank and suspected water loss.
- Excess water consumption - Their homes water use increased 8,000+ gallons a month following completion of the pool.
- When the solar system activated, the surge tank level dropped so much that the fill line turned on.
- For a while each day after the systems shut off, water backs up out of the slot and onto the pool decks.
The bottom line - The hydraulics of this project were not planned or executed properly.
Surge Tank Sizing
The surge tank was too small and was installed at the wrong elevation relative to the pool. The surge tank was also not sized sufficiently to accommodate the draw down for the solar system.
Due to the tank being under sized, when the solar panels filled, the tank's operating level dropped and the fill line sensor activated. The tank would then eventually return to it's proper operating level with make-up water from the water meter.
However, when the systems shut off, the water in the solar panels would drain down into the tank. Now the tank is too full.
As the level in the tank rose above the overflow line, it backed up into the gravity drain line and out of the perimeter overflow slot. The water collects on the pool deck the until the tank's overflow line can drain water to waste. Repeat this process everyday, and it amounts to over a hundred thousand gallons of wasted water.
Not to mention the wasted money for the water, energy to heat and filter that water and the chemicals to treat it.
Bather Displacement
When bathers swim in the pool, their body mass and movements displace water into the surge tank.
The relative shallowness of the surge tank, cause the tank's water level to rise above the over flow line. Valuable water is needlessly discharged into the storm drain, just from swimming in the pool.
Proper Calculations
There is no such thing as a surge tank that is too large.
Proper sizing of a surge tank needs to provide freeboard (excess empty tank volume) below the over flow line, so that the pool can actually be swam in without discharging water into the storm drains. Imagine, people actually swimming in a pool... what a novel idea!
The surge tank also needs to have sufficient volume of water in storage, to allow for the draw down effect that occurs when the system first starts up each day. Since the pumps draw from the tank, the level in the tank will continue to drop until that water reaches the pool, fills the gutter and gravity drains back to the surge tank. This volume of water is called water in transit.
Additionally, an amount of water must be stored for other demands that will be placed upon the surge tank. If fountains, solar panels or water feature pumps will also draw from the same surge tank, then a volume of water in transit must also be provided for these features.
Finally, a protective level of water must be maintained in the tank to prevent any of the pumps from running dry. This is called the minimum operating level (MOL). This level is usually 12 inches, but it may need to be deeper depending upon the size of the pumps. High horsepower pumps can easily vortex in 12 inches of water.
The sensor for the auto-fill will be set just above the MOL. This is to ensure that the water level in the tank never drops below this safe level.
Surge Tank Elevation
The slope of the gravity drain lines and the distance of the surge tank from the pool, will determine the entry point of the gravity drain line into the surge tank. The further away from the pool the surge tank is place, the deeper below grade it will enter the tank. Obviously this also increases the cost of a site fabricated tank. Manways, ladders or increased tank heights all contribute to additional costs.
The maximum operating volume of the tank is the tank's volume that exists below the entry point of this gravity drain line. So if the gravity drain line penetrates the surge tank too low, the tank capacity is greatly diminished.
The solution? Build the surge tank deeper below the entry point of the gravity drain line.
Planning
Of course getting all of these volumes and elevations correct requires a lot of planning. Perimeter overflow pools cannot be designed without creating cross-sectional drawings.
The locations of the various pipes (overflow and fill lines, sensor stand pipes, suction drains, vacuum port) and the entry point of the gravity drain line must all be carefully calculated.
Always a Solution
Sometimes the surge tank needs to be relocated closer to the pool, in order to raise the entry point of the gravity drain line.
When space is limited, our firm builds the surge tank adjacent to the pool. This allows for sharing a common wall and reducing construction costs.
If the tank size and depth is constrained by project parameters, then we may specify balancing valves. Of course balancing valves only work if the tank can be built slightly above the pool, say in a nearby planter or in an elevated portion of the patio.
Knowledge and Planning... FOR SALE HERE.
Paolo Benedetti, Pool Designer, Aquatic Artist, Watershape Consultant, Expert Witness, International Construction Management
Contact the author at: info@aquatictechnology.com or 408-776-8220 "Creating water as art."™
Aquatic Technology Pool and Spa© ©www.aquatictechnology.com
All rights reserved.
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