LEAKAGES FROM DAMS.

New Zealand Herald, Volume LXIV, Issue 19698, 26 July 1927, Page 7

LEAKAGES FROM DAMS.

TREATMENT BY CEMENTATION

Methods adopted to arrest leakages from dams where the foundations were not impervious, were reviewed by Mr. A. A. Barnes in a paper read at the meeting of the Institution of Water Engineers at Scarborough. He said that neairly 20 years ago Mr. H. P. Hill h'iwi been faced with the problem of stopping leakage, to the extent of more than a million gallons a day, from two of the three Walshaw Dean reservoirs of the Halifax Corporation. Mr. Hill had been conceived the idea of introducing irato boreholes in front of the core wall a very dilute mixture, consisting of 1 part of slow-setting cement and 20 parts of water. It was found next day that the quantity of leakage had -been reduced. Further boreholes were drilled and treated in the same manner, and the leakage was gradually stopped. Altogether, 97 boreholes, sin. in diameter, were drilled, and 1386 tons of cement were used. The largest amount taken by one borehole was 157 tons 12cwt. Cementation had been adopted in the case of the Bar'tley reservoir of the Birmingham Corporation. The cost of the two large cementation contracts involved totalled £35,851. With an overall consumption of 35.9 tons of cement per borehole, and with holes 101 ft. deep, thr average cost worked out at £278 per completed borehole. The boring and cementation work had been completed before the contract for the actual embankment was advertised. Mr. Clemesha Smith, in the course of discussion related how he had dealt with a leakage of 1.000,000 gallons a day from a Wakefield reservoir. The estimated cost of extending the trench was £25,000. but boreholes were made and cementation introduced, with the result that the problem was effectively dealt with at a cost of £4OOO.