In our last post, we talked about the latest codes to affect water features, which is the CDC’s Model Aquatic Health Code. This code was written by committees with many people involved in the aquatics industry but very few with experience designing fountains. This was unfortunate, as there are circumstances that fountains are challenged with, that spash pads that are within an aquatic venue never see.
Remember as you read this that we are assuming that most State health departments will be adopting the new MAHC into their swimming pool codes.
Here are some of the challenges and differences between an aquatic venue splash pad and an interactive fountain:
- Location – the aquatic venue is a controlled space, you are made to wear a bathing suit or in the case of small children, swim diapers, you are encouraged to shower before entering the pool area and normally you are forbidden from eating around the pool. Many interactive fountains and some splash pads are located in public spaces like outdoor malls, public plazas and parks. There are no restrictions with respect to clothing and often times both kids and adults will enter the fountain fully clothed. The public plaza fountains are often located near eateries and coffee shops and you can even find people letting their dogs play in the water.
- Debris – the protected aquatic venue environment has a hand up on the control of debris that can enter the water feature. While they still have to deal with hair and lint, those issue are somewhat mitigated by the pre-swim shower. There are often no trees in the pool play area. On the outdoor water feature, they are often built as part of a park system and you are likely to find adjacent to the fountain a playground and large expanses of grass and planting. This brings into play the decomposed granite (DG), re-used rubber, or wood mulch, that is often used in the playground area and tracked into the fountain on the feet of the kids and parents. Additionally, newly mowed grass will find its way into a fountain by way of wind and shoes or feet along with whatever other organic material happens to be on the grass (read geese and dogs). Any park or plaza will have landscape planting (meaning trees and shrubs) with spring bloom material (fines) and fall leaves along with the always present bark mulch that tends to decompose into fine fibers.
- People – Here the difference is most glaring. On one side we have the swimsuit clad, swim diaper wrapped, hopefully they had a shower pool patron, and on the other side we have the fully clothed, partially sweaty, maybe poopy and oh darn I just walked through that spilled milk shake family member that is going to take advantage of the free water park spray pad to cool off in.
- Weather – When it storms, it rains in the pool. When it storms around a fountain it blows all that debris we spoke about indiscriminately around the area, and since the fountain is designed to drain, right into the cistern.
Which brings me to the question that is the subject of this post ….. how much water should that cistern contain? When the MAHC came out, I searched the document so see what they would say about cistern size, but they only addressed it in context to a gutter pool, 1 gallon for every square foot. If you were to interpolate this, which is never a good idea, a pool occupancy (MAHC 22.214.171.124.5.3) of 10 square feet per bather would have us size cisterns at 10 gallons per bather. An interactive deck is rated at the same 10 square feet per bather.
Interactive fountains are usually fairly compact areas so let’s look at a space that is 50’ in diameter. The area in the 50’ is 1962 square feet which would dictate a cistern size of 1962 gallons. Is this enough? California requires a minimum of 4000 gallons and both California and Florida state a minimum of 3 times the flow rate of the display pumps and filter pump. Looking back at our 50’ fountain, let’s say it has 50 jets using 20 gpm each, for a flow rate of 1000 gallons. This would dictate a volume of 3300 gallons (1000 + 100 gpm filter for 30 minute turnover x 3). Is this enough? The answer is no and no.
Our experience has been that the larger the volume of water the easier it is to keep up with the loading that one might see at an interactive venue, and we have settled on a minimum of 5000 gallons. This volume is a comfortable size for the sizing of filter and treatment equipment, in some of the conditions, we have to place them in and maintaining a chemistry balance. Remember when dealing with interactive water features you never know how many people will get in it at once and put a higher demand on filtration and treatment.
There are other steps we take to manage the debris loads, but those we will discuss in coming posts.