Eilat 's artificial lagoons project on the Red Sea - Israel R. Raviv Ir. R. Raviv, Coastal Engineering Ltd., P.O. Box 7322, z/b 37072, Introduction Eilat city is located in the southern part of the state of Israel on the coast line of the Red-Sea, 10 Km west of Aqaba city in Jordan. The Red Sea is one of the most interesting seas in the world for scuba diving and it makes Eilat the most attractive area for recreation in Israel. Swimming, scuba diving, sailing, water skiing, wind surfing and other recreation activities can be enjoyed in Eilat throughout the whole year. In the year 1992 it was decided by the Eilat Foreshore Development Company Ltd. which is a government company to continue with the realisation of the master plan consisting of the Artificial Lagoons project. The building of the project will enable the company to provide more areas for building hotels (3,000 rooms), enlarging the existing marina, and providing more swimming area by adding a 1000 meters length of water line with sandy beaches. Construction works were started in September 1993 and are expected to be finished in September 1995. Project Description The project includes: A swimming lagoon, called the eastern lagoon. This lagoon is connected to the sea by a canal 300 meters long which is bridged by two bridges. One bridge for pedestrians, close to the coast line and one a traffic bridge near the lagoon. A sail ing lagoon, called the middle lagoon with a peninsula. This lagoon is connected to the existing lagoon on the west side of the project (which was constructed 30 years ago) by a canal. This canal is also bridged by two bridges. One moveable bridge for heavy traffic and one moveable bridge for pedestrians. The existing western lagoon is an inner marina surrounded by
320 Marina hotels. This lagoon is connected to the open sea by a canal and an outer marina. This canal is also bridged by a pedestrians moveable bridge. The total berths in the middle lagoon together with the existing western lagoon and the existing outer marina are 500 places. Design Data Waves: From south direction. 2-3 meters significant heights with period of 6 to 7 seconds, wind force of 40 knots and effective fetch up to 150 nautical miles. Storms: 3 to 5 times per year during winter time: December- February, with a duration of 1 or 2 days only. Tide: +0.90 meter; -0.60 meter, once per year. +1.17 meter; -0.78 meter, once per 10 years. +1.29 meter; -0.86 meter, once per 25 years. Design Requirements Swimming - Eastern Lagoon 1. Water quality will be controlled by the daily tide fluctuation and must comply with Israel Ministry of Health requirements. 2. The slopes 1:15 to 1:20 will be covered by 50cm sand layers. 3. Water depth 2.5 meters maximum. Middle Lagoon 1. The peninsula will be built with vertical walls. ^ 2. Vertical kg/m\ surcharge load for the walls: 500 kg/m to 1000 3. The surroundings stones. will be built with slopes 1:3.5 covered by 4. The water quality fluctuation. will be controlled by the daily tide 5. Water depths 2.5 meters. 6. Jetties supported on piles. Canals 1. 2. The slopes will be built 1:3.5. Water depth 2.5 meters. 3. Water velocity maximum 0.15 meter/second. Breakwaters for water intake for swimming - Eastern Lagoon 1. Will be built from local red granite stones. 2. Water depth at the entrance 2.5 meters.
Typical design crossection of the project 1. Swimming ff Eastern Lagoon Marina 321 a. Slopes of 1:20 or 1:15 in relation to walking safely into water and minimizing the maintenance of the 50 cm sand layer. b. The sand grains diameter 0.42mm to 0.85mm, to prevent being blawn by the wind and due to marine biological requirements. 2. Middle Lagoon a. Vertical walls - Quay walls are designed from deep diaphragm walls. 60cm thick. The soil consists of sand and clay layers. The horizontal cross sections of the walls can be straight or T shaped if necessary. b. Total walls length in the project 500 meters. Wall thickness 60cm and wall length varies from 12 meters to 14 meters. 3. Bridges a. All bridges are based on deep diaphragm walls straight or T shaped with 60cm thickness. b. Moveable parts are designed according to Dutch standards and manufactured in the Netherlands. Special construction problems 1. The lagoons were excavated in dry conditions. The groundwater surface was lowered by well points at the beginning of the work and immediately after were kept low by open air pumping. The ground water surface was lowered 3 meters on the whole surface of the lagoons, so all works could be done 2. in dry conditions, between the elevation +3.0 meters above sea level and -3.0 meters under sea level. 800,000 cubic meters of earth was removed and spread around the project in compacted layers of 30cm thick. This was done in order to create new landscape around the project. 3. During the canals excavations the foundations of 4 bridges and 200 meters jetty were executed by diaphragm walls. 4. The front side of the diaphragm walls was covered by 3 cm of finish layer of torquecrete between the elevation +0.70 meter and -1.0 meter. This was done while the middle Lagoon and the canals were still dry by continuous pumping of groundwater. Above the elevation +0.70 the concrete was poured in moulds.
322 Marina Contractors and tenders The project was tendered in stages because the design was done by stages. It was done, of course, according to an approved master plan for this area of Eilat. The first stage of the project which was tendered includes: The Lagoons, Canals, Breakwaters of the water intake of the Swimming - Eastern Lagoon, Diaphragms walls: For quay-walls, jetties, bridge foundations. All of that up to the elevation +1.5 meter above sea-level. This elevation was chosen to enable to dig the lagoons and canals without interference while constructing the bridges. This tender was given to one contractor to be constructed during a period of 24 months. The second stage of the project which was tendered a few months later includes the parallel construction of the four bridges, from the elevation of +1.5 meter above sea level up to the final elevation of each bridge as designed. During the construction period of this huge project, "life" was going on in that concentrated tourist area with 3,500 hotel rooms. This with a lot of patience, exact and sharp working schedule, while using special fence - curtains, trying to keep the view as nice as possible. Project plan's and photos Annexed to this project description one can see the following: Annex No 1: A photo of the project maquet. Annex No 2: A map of the Red Sea showing Eilat and Aqaba. Annex No 3: Typical cross section of the Eastern - Swimming Lagoon. Annex No 4: Typical cross section of canal and breakwaters for water intake to the swimming Lagoon. Annex No 5: Typical cross section of the Inner Lagoon. Annex No 6: Typical cross section of the Sailing canal between the Western-Existing Lagoon and the Middle Lagoon. Annex No 7: Typical side view of the Moveable Traffic Bridge. Annex No 8: Typical side view of a Moveable Pedestrians Bridge. Annex No 9: Typical side view of a fixed Traffic Bridge. Annex No 10: Typical side view of a fixed pedestrians Bridge. Annex No 11: Typical cross section of a jetty and Bridge. Annex No 12: Typical side view of a jetty and Bridge. Annex No 13: Typical cross section existing western lagoon. of a quay-wall in the
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324 Marina Annex Mo 2= A nap of the Red Sea showing Ellt and Aqaba. Annex No 4:_Topical cross sections of canal and breakwaters for water-intake tc the su.nning LuQOon. Inland p.00 Annex ho 3: "fypycal cress section of the Eastern - Suinning Lagoon.
Marina 325 Annex Mo 8-' Tupical side view of Q Moveable Pedestrians Bridge
326 Marina Annex 1?: Typical. Sioie View of c jetty and bridge. \ Annex No 13: Typical cress sections of a Jettu and bridge. Annex 13: A Typical Cross section of a quay wall in the existing Western Lagoon.