Engineering Wonders of the World
Volume III

190 ENGINEERING WONDERS OF THE WORLD. below high-water level. This dam divides the contents of the reservoir into three portions : a top slice, 40 feet thick, cov- A Submerged erjng ^he whole area of the reservoir, and available for compensation water or for withdrawal through the aqueduct ; the water below a horizontal line drawn from the crest of the submerged dam to the Caban Coch, for compensation purposes only ; and that impounded by the submerged dam independently of the Caban Coch. The aqueduct, it should be mentioned, has its intake immediately above this dam. The next of the series, the Pen-y-Gareg, is 123 feet high, and creates a reservoir of 1,320,000,000 gallons ; the third, the Craig Goch, is 120 feet high, and impounds 2,000,000,000 gallons. When th© other three dams have been built the total storage capacity of the sys- Pen-y-Gareg ® r and Craisr tem will total 17,960,000,000 / “ k ’ ’ Goch Dams. gallons, or about one and a half times the quantity of water impounded in Lake Vyrnwy. All surplus water passes over the crests of the dams, forming in flood seasons a series of magnificent waterfalls, set in most beautiful surroundings. The reservoirs cover the sites of two houses associated with the poet Shelley, a church, a chapel, a school, and a number of cottages. All of these buildings were demolished, and most of them replaced by new structures on PEN-Y-GAREG DAM, ON THE ELAN RIVER. LENGTH. 417| FEET; HEIGHT, 123 FEET. (Photo, F. Milner.)