The Columbia Parks and Recreation Department is starting to fill empty slots among its aquatic center lifeguard staff. The department received 10 applications after it put out a call last week seeking staff. There needs to be a minimum of 70 guards to be able to open pools. Only 46 guards are on staff as of Friday. "Our staff will follow through with (the 10 applicants) to get them registered for training," department Marketing Specialist Tamara Miller wrote in an email. Guard training will happen Tuesday through Thursday, June 4-6, June 14-16 and June 18-20. Sessions are free for those employed by the city.