flood protection scheme for mina | feature stories 1 2 3 4 1 Night mass concrete pouring using cranes and buckets 2 Western Shoeib dam during construction overlooking the pilgrims’ tents in Mina Valley 3,4 Completed Majar Al Kabsh dam (after Jan 2008 floods/downstream view) 5 Aerial view of flood protection works; Mina’s white tents appear in the foreground (base map courtesy of Google) 6 Damage to Mina area after January 2005 flood 7 Channels under construction 8 Channels viewed from the Mina Valley Challenges Site investigation, detailed design and the subsequent bulk of construction works had to be carried out between two Hajj seasons - a period of less than 11 months. Any sign of construction including access ramps, site temporary contractor facilities or heavy equipment had to be dismantled or cleared prior to the onset of the Hajj. To cope with the very tight schedule, concrete pouring had to be done during the hottest time of the year, and temperatures recorded in the summer of 2007, when most of the construction was carried out, were record breaking. Heat was a major factor affecting all aspect of concrete design from the concrete mix components, to the pouring sequence, and cooling requirements. But following strict design measures for pouring and curing proved to be successful as no temperaturerelated cracks were observed when the works were completed. The cement content was minimized and water was introduced to the concrete mix in the form of ice flakes in an effort to reduce hydration heat effect in 40°C temperature. Concreting for the entire project always took place during the night hours when temperatures were relatively low and solar radiation absent; the cold mix was intermittently transported from the batching plant in Muzdalifah to each dam in mixer trucks. Access to the dams, tunnel portals and channels, another construction constraint in the mountainous area around Mina, was remedied with the installation of steep ramps affixed onto the mountains’ steep sides for easy access and the construction of a permanent access road reaching the channels. Considering the time and heat factors, and the difficult site conditions, Mina’s flood protection project is a remarkable achievement in efficiency, speed and careful calculation. Since completion at the end of 2007, the scheme has been twice put to test, and each time Mina remained dry and sediment-free, the dams effectively storing the stormwater and the entire tunnel and channel networks working as predicted within a considerable margin of safety. 5 6 7 8 11