Placed on tees by an unseen, automated machine, the white balls pop up through small openings in the green practice mats, their dimpled surfaces a study of shadows under the stadium lighting. A chorus of whoosh-thwack echoes through Haggin Oaks’ driving range, where a handful of night owls and a security guard occupy the largely desolate facility. Groundskeeper Erin Hill says he incorporates golf swinging practice into his work by hitting balls to a certain part of the range, where he will later pick them up with his cart. Haggin Oaks groundskeeper Erin Hill, 38, clears the driving range of golf balls July 3 during his night shift from 10 p.m.