** Shares of Australia' GR Engineering Services GNG.AX surge as much as 4.8% to A$5.05, logging their biggest intraday pct gain since April 1
** The company, which provides engineering design and construction services to miners, says it has executed an A$229 million ($163.5 million) contract with a unit of Genesis Minerals GMD.AX for services in the Tower Hill gold project
** Around 520,936 shares change hands, 2.8x the 30-day average trading volume
** Stock up 13.5% so far this year
($1 = 1.4035 Australian dollars)
(Reporting by Shruti Agarwal in Bengaluru)
((Shruti.Agarwal@thomsonreuters.com))