Pool Engineering
- Water volume: The 1927 pool was as deep as 22 feet in some places. The restored pool has a flow-optimizing mean depth of 6 feet which will effectively reduce the water volume in the pool by half.
- Exchange area: The 1927 pool had three 24-inch intake openings. The restored pool has three 8X16 foot intake openings and three 5X12 foot outflow openings. The total of over 600 square feet of water exchange is more than 25 times the size of the openings in the old pool.
- Circulation rates: Mechanical standards for fresh water pools is three changes per day. The 1927 pool circulation rate was about once every three days. The restored pool is engineered to turnover 3-10 times per day (1.8 million gallons per change), a 10-30 fold increase in water exchange over the 1927 pool design. By comparison, nearby Kuhio Beach has no intake or outflow system and no measurable water exchange rate.
- Sludge abatement: The natural reef bottom of the 1927 pool has degraded into a silty sludge that will be encapsulated in the restored pool. Demolishing all or any part of the pool walls would release this sludge onto the reef and into the water at Kaimana Beach.
- Visibility and Swimmer Safety: The restored pool is much more shallow than the 1927 pool. It is also lined with a special silica sand which will not discolor nor organically breakdown like coral sand (and create the cloudy sediment that plagues Waikiki). The silica sand selected has a large grain size to settle quickly if disturbed by swimmers and a light color to optimize visibility for water safety personnel.
- Restoration engineering team credentials: UH Ocean Engineering Chairman emeritus, Dr. Franciscus Gerritsen and Dr. Karl Bathen are the ocean engineers that designed the Koolina swimming lagoons. In addition to more than 25 years of study of Waikiki’s coast waters, Drs Bathen and Gerritsen performed site-specific measurements of coastal flow to inform the design of restored pool. Dr. Gerritsen’s federally-funded Sea Grant found a unique current pattern that is the basis of the Natatorium’s circulation design. On the other hand, the US Army Corps’ work in the area under Gov. Burns and Mayor Fasi severely misjudged offshore current conditions. Their proposed series of groins were revealed in US District Court NEPA hearings to cause major erosion of sand along beaches.
THE FACTS:
WAIKIKI WAR MEMORIAL NATATORIUM
“I did not believe that I could ever get a thrill out of a swimming meet after all I have seen and competed in. But last night (at a meet in the Natatorium), I certainly had the thrill of my life – the crowd. I will never forget it. The intense interest shown by everybody, the color, that wonderful Waikiki pool, I had to rub my eyes and pinch myself to see if it were not all a dream.”
-- Duke Kahanamoku
More About the Waikiki War Memorial Natatorium
HISTORIC HAWAI‘I FOUNDATION
