Category Archives: Construction

Minimum Water Depths Under Starting Blocks

On July 20, 2012, the Facility Design and Construction Model for the Model Aquatic Health Code (MAHC) was posted for public comment due October 14, 2012.  In section 4.8.3.3. a single sentence could change the industry standard for minimum depths  under starting blocks to 6 feet and 7 inches for a distance of 20 feet.  This could have a significant impact on swimming pools around the country and industry professionals are encouraged to participate in the public input process.  In order to make an informed decision, the following data is offered for consideration. 

Competitive swimmers execute headfirst dive entries from starting blocks into pools where water depths can vary. If the swimmer’s head strikes the bottom of a pool, this could result in damage to the cervical vertebrae, thus may result in quadriplegia. This was a significant topic of conversation in the industry in the early 1980s when a varsity swimmer at a university was injured in practice. Before 1970 this was unheard of, but in the early 70s, goggles were introduced and different methods of completing racing dives were developed to maximize speed and minimize the potential for losing goggles.  

In prevention of Cervical Spinal Injuries (CSI), a cohesive plan currently does not exist for a minimum uniform water depth, which would lessen the likelihood of catastrophic tragedies. “No Diving” signs are posted when the water is less than five feet deep in some states, and four feet in others. There is still more inconsistency. What is the right depth for balancing safety and function for underneath starting blocks? Moreover, should we build all-deep water pools? What depth? And what about recreation swimmers?  

Here’s the Confusion

Up until the early 2000s the industry standard water depths were in the 3 feet 6 inches to 4 feet range. November 2001, the National Federation of State High School Associations (NFHS) changed minimum water depths from 3 feet 6 inches to 4 feet. USA Swimming followed suit with a note that teaching off a starting block shall be limited to 6 feet water depth. 

Policy makers, swimming pool rulebooks, and state swimming pool codes still lack research in regard to water depth requirements under starting blocks. Moreover, water depth requirements under starting blocks in governing bodies’ rulebooks not only conflict with one another but often conflict with state statutes, which may in turn conflict with local county and municipal ordinances.  

The following shows a variance among the four aquatic governing bodies, as well as the YMCA and the American Red Cross, in regard to water depth for headfirst entries. 

Federation Internationale DE Natation (FINA): 4 feet 5 inches.

National Collegiate Athletic Association (NCAA): 4 feet.

National Federation of State High School Associations (NFSHS): 4 feet.

USA Swimming and US Masters Swimming: 4 feet for racing, 6 feet for teaching.

YMCA: 5 feet.

American Red Cross: 9 feet.

 

The Research

The Counsilman Center for The Science of Swimming completed a study in 2011 on racing start safety published in the International Journal of Aquatic Research and Education.  Joel Stager, Director reports the water depth needed to prevent contact with the bottom of the pool that could result in injury is well beyond 6 feet 7 inches and the critical link to safe starting block starts is education.  In summary this research indicates:

  1. Swimmers go deeper in deeper water
  2. Older swimmers go deeper than younger swimmers
  3. All ages ( and experience levels) of swimmers go shallower when asked to do so
  4. There are differences in head depth as a function of block height
  5. Virtually all starts are fast enough to cause injury if an impact should occur
  6. Very few swimmers go deeper than five feet even in seven feet of water. 

We are at a crossroads between safety versus programming when they should be compatible.  The key to safety in this matter is instruction and how participates learn how to dive.  The reality is no water depth is safe without proper instruction.  When making an informed decision, one must balance the threats and benefits from an activity.  There has been plenty of research on the health advantages of recreation, lesson, fitness, and competitive swimming and how it impacts safety and lifestyle. Here’s a nice shout out to water safety programs and ongoing swim lessons nationwide. Even though more and more people are exposed to a growing number of swimming pools at new aquatic facilities across the nation, drowning death rates in the United States have declined in the last decade according to the Centers for Disease Control and Prevention.  

 

Should We Build All-Deep Water Pools?

Is the answer that we build all-deep water pools? And if so, how deep? Twenty years ago swimmers swam nearly their entire race at the surface. Today most elite swimmers swim a large percentage of their races 3 to 4 feet below the surface, utilizing a butterfly (dolphin) kicking technique.  

Championship pool depth may impede many instructional, fitness, and recreational opportunities and consequently, revenue potential. And since people frequent pools for a variety of reasons—fitness, relaxation, instruction, competition, and therapy—today’s swimming facilities do not just accommodate competitive swimmers but are multidimensional centers encompassing all types of swimmers.  

To provide a fiscally sustainable facility, multiple users must be able to use the same space for different purposes at different times. Building an all deep-water competitive pool would significantly limit other uses such as recreation, lesson, fitness and therapy.  The following shows preferred water depths for various types of swimmers. 

0 – 3.5 Feet

        Toddlers

        Recreation

        Wellness / Therapy 

3.5 – 5 Feet

        Recreation

        Lap Swimming

        Wellness / Therapy 

5 – 10 Feet

        Competitive Swimming

        Water Polo

        Synchronized Swimming 

11.5 Feet +

        Diving

Unintended Consequences

Some may suggest that the Facility Design and Construction Module is limited to new construction and would not apply to existing facilities.  I would suggest that given the United States legal system this is naive.  I cannot envision an outcome that defines separate solutions water depth solutions for new and older pools.  In 2001 when the NFSH changed the minimum depth standard from 3 feet six inches to 4 feet, many high school pools moved the starting blocks from the shallow end of the pool to the deep end.  For pools without diving wells, this proposed change would likely require structural modifications to the pool shell.  To renovate a six lane 25 yard pool from a maximum water depth of 4 feet to 6 feet 7 inches for a distance of 20 feet in front of the pool edge is estimated to be in the $200,000 range.  Not only will the pool depth be effected but the mechanical equipment will need to be upgraded to services the increased water volume.  For new construction the differential cost is not as great with an estimated increased cost in the $20,000 range.  

Conclusion

The State of Michigan is the only state that requires water depths under starting blocks to be 6 feet 7 inches.  If the MAHC codifies this unique standard it will change the national standard as defined by the governing bodies of sport.  In this writer’s opinion, the unintended consequences maybe the dramatic decline of competitive swimming activities in the United States similar to the effects of removing high dives across the country in the 1980’s and 1990’s.  If this happens what are the negative health effects on childhood obesity and an increased sedentary lifestyle? 

 

All Stories

Birmingham CrossPlex To Host NCAA Division II Swimming Championships

The NCAA has announced that they will be hosting the Men’s & Women’s NCAA Division II Championships at the Brimingham CrossPlex.  The Birmingham CrossPlex is a world-class facility designed for three primary sports: indoor track and field, volleyball, and competitive swimming and diving. Located just two miles from theBirmingham-SouthernCollegecampus, the Birmingham CrossPlex is proud to begin hosting events that will attract athletes, coaches, and spectators from all over the world.

The team of Counsilman-Hunsaker and Davis Architects designed the state-of-the-art natatorium with the ability to hold 1100 spectators in the stands and 500 athletes/coaches on the deck. The facility features a 50-meter competition pool with bulkhead, which not only accommodates multiple racing and training configurations, but also features a flow-through design which minimizes waves rebounding on turns. The extra deep concrete/tile gutter system creates a calmer pool, thus reducing the amount of turbulence swimmers must face.

12,600 sq. ft. Competition Pool

  • Ten 50-meter lanes
  • Twenty 25-yard lanes
  • Depth ranges from 7 ft. to 13 ft.
  • Fiberglass movable bulkhead to accommodate multiple racing and training configurations
  • Two 1-meter and two 3-meter springboards
  • Generous decks all around the pool
  • Regenerative media water filtration
  • Ultraviolet water treatment system
  • Extra-deep concrete/tile gutter system
  • Water polo

Relative to the structural design of swimming pools, which codes and standards apply?

All fifty states adopt the International Building Code (IBC) as their model code. IBC is published by the International Codes Council. Most states also have a “state specific” code, as well as some cities. Within IBC, Reference Standards are used. These Reference Standards are material-specific or use-specific, typically written by industry organizations. So, the code methodology for swimming pools can be summarized as follows: 

1.     Model Code (IBC)

     a.     State Code

          i.    City Code

     b.    Reference Standards

          i.    Loading: American Society of Civil Engineers (ASCE 7) 

         ii.    Concrete: American Concrete Institute

1.     ACI 318: Building Code Requirements for Structural Concrete

2.     ACI 350: Code Requirements for Environmental Engineering Concrete Structures

3.     ACI 350.1: Tightness Testing of Environmental Engineering Concrete Structures

4.     ACI 350.3: Seismic Design of Liquid-Containing Concrete Structures

5.     ACI 350.4: Design Considerations for Environmental Engineering Concrete Structures 

The International Building Code (IBC), all editions, includes swimming pools within the definitions chapter and in Section 3109 of the “Special Construction” chapter. A swimming pool is defined in IBC as “Any structure intended for swimming, recreational bathing or wading that contains water over 24 inches in depth.” Section 3109 deals solely with enclosures and safety. 

Because IBC references Swimming Pools, all pools must be designed to comply with IBC. Therefore, all pools must comply with ACI 318. ACI 318 is primarily a “life-safety” code with minimum durability and serviceability requirements. This code is used to design pool shell thicknesses and reinforcing. ACI 318 states “For special structures, such as …tanks…, provisions of this code shall govern where applicable.” The commentary of this section refers to ACI 350 for “…Special emphasis is placed on structural design that minimizes the possibility of cracking…” While not specifically required in the design of pools, ACI 350 is a recommended standard for durability and serviceability. 

ASCE set forth the loading criteria for all structures. This is used to determine the soil pressure, groundwater, etc. against the walls and slabs of pools. So, the methodology for the structural design of pools within ACI is as follows: 

1.     (Required) Loading: American Society of Civil Engineers (ASCE 7)

2.     (Required) ACI 318: Building Code Requirements for Structural Concrete

     a.     (Option) ACI 350: Code Requirements for Environmental Engineering Concrete Structures 

There is a new code available this year, the 2012 International Swimming Pool Code (ISPC), published by International Codes Council. No state has adopted this code yet. ISPC references ACI 318 as the standard. So, the structural design of pools is still the same.

 

 

Shotcrete

Many people use different definitions for the term “Shotcrete”. To clarify, the International Building Code (IBC), Section 1910 clearly defines “Shotcrete” as “…a mortar or concrete that is pneumatically projected at high velocity onto a surface.” The American Concrete Institute (ACI) ACI 506 (Guide to Shotcrete) further defines shotcrete as a “wet-mix” process and “gunite” as a “dry-mix process”. Both shotcrete and gunite are defined as “Shotcrete”.

From the terms above, you can see that shotcrete is purely a method of placement. It is not a design process. Therefore, whether the pool shell placement method is shotcrete or cast-in-place, the design method is still the same. Don’t let anyone tell you there is a difference in the design. There is not!

 

Measuring The Olympic Aquatic Facility Course

If you’ve been watching the Olympic swimming events, you’ve probably been noticing all the exciting finishes and as the athletes win their medals.  What you have likely missed is the tiny target marking on the edge of each lane.  This target is what the surveyor uses to accurately measure the length of the pool each day.