HAPPENIN’ OTSEGO for MONDAY, AUG. 14 Concert At Pierstown Grange CHAMBER MUSIC CONCERT – 7:30 p.m. The public is invited to the annual Florence High Memorial Chamber Music Concert arranged by Glimmerglass Festival Violinist Ubaldo Valli. Pierstown Grange Hall, 137 Wedderspoon Hollow Rd., Cooperstown. Call (607)264-3069 or (607)547-1347. WATER SAFETY – 10:30 a.m.-1 p.m. Children aged 11-14 have fun in the pool while learning about water safety and lifeguarding with the Oneonta YMCA. Cost, $35 members, $50 public. Briggs Pool, Wilber…