DEL MAR, Calif. – Del Mar’s beleaguered turf course underwent its most extensive aeration of the season and was watered to the equivalent of a quarter-inch of rain Tuesday in an effort to alleviate the firm conditions that have plagued the course since the July 17 start of the meeting. The turf course is scheduled to be used for three races Saturday after a break of nine days between grass races. Four horses were euthanized as a result of injuries suffered on the course July 17-26, and another was seriously injured in a race July 31, leading to the temporary cancelation of turf races. No grass races were held for a period of six racing days – Aug. 1-3 and Wednesday through Friday this week. Turf course superintendent Leif Dickinson said the aeration conducted Tuesday “was a little bit more extensive” than an aeration procedure conducted the preceding week. Dickinson said the course underwent a Verti-Drain procedure designed to loosen the soil by plunging tines into the surface. “It pitchforks into the ground and fractures the soil,” he said. :: DRF Live: Get real-time updates and insights from DRF reporters and handicappers at Del Mar each race day Starting after dusk Tuesday and until dawn Wednesday, the course was watered at a rate equivalent to a quarter-inch to one-third of an inch of rain, Dickinson said. The course could be extensively watered again before turf racing resumes Saturday, he said. “What I did is what I usually do on Sunday nights, which is two days prior to a normal racing day,” Dickinson said. “This time, we put it off until Tuesday. We’ll check to see if we need to do it again tonight. We have to do what we think is right to set it up for racing.” The top race Saturday is the $150,000 La Jolla Handicap for 3-year-olds over 1 1/16 miles on turf. The race has a projected field of five, including Enterprising and Argyle Cut, the first two finishers July 17 in the Oceanside Stakes, as well as Sammy Mandeville, Schoolofhardrocks, and Tonito M. When turf racing does resume, the course will be used for an average of two races per day through the Sept. 3 end of the meeting. No turf sprints will be held, and claimers can only run through optional-claiming races, according to Tom Robbins, director of racing.