Richard J. Baier, Alexandria’s director of transportation and environmental services for almost 15 years, will resign Aug. 31 to become director of public works for Sumter County, Fla., near his parents and other family members.

Baier, 51, has led the 212-employee department with a $44.9 million operating budget since January 2000. He previously was public works administrator for Clearwater, Fla. and held several positions with the Florida Department of Transportation.

“I’m looking forward to getting home to Florida, where my parents are, my sisters live and my [younger] son is going to college,” Baier said Tuesday. “But I’ve been in Alexandria so long that it’s part of me — this is bittersweet.”

He’s the third high-level Alexandria city employee to announce his departure this summer. City planning director Faroll Hamer retired last week, and deputy city manager Michele R. Evans, who worked for the city for 37 years, will retire Aug. 1.

Baier, a professional engineer, is no stranger to controversy in Alexandria, having just weathered a civic dispute over installing bike lanes on a residential portion of King Street. He also led the city’s eco-city initiative, implemented the commonwealth’s first dedicated bus rapid transitway, expanded local bus routes and oversaw the launch of Capital Bikeshare in the city.

He also oversaw significant expansion of the city’s solid waste collection programs, and led the department to national accreditation for the first time in 2006, with reaccreditation in 2010 and 2014.

“Rich has been a pivotal leader on a variety of issues crucial to Alexandria,” city manager Rashad Young said in a statement. “He has helped shape the city’s approach, and delivery of services, in areas ranging from transportation infrastructure and engineering to solid waste collection and environmental quality. Rich’s energy and commitment to civic engagement have been remarkable.”

The city will launch a nationwide search for Baier’s replacement.