The officers, who were white, claimed that they had faced retaliation from Colarulo and others when they complained in 1998 about discriminatory treatment of black officers in North Philly's 25th District, where Colarulo was then captain.
The officers were awarded a $900,000 settlement in 2009.
Zienkowski said that the township's solicitor and labor council spoke with a number of people involved with the lawsuit and came away believing that Colarulo was still the right person for the job.
"We put a lot of weight into this decision," he said. "Based on the work Bill did in a city as large as Philadelphia, and his overall philosophy, we feel he's the right candidate."
Colarulo joined the Philadelphia Police Department in June 1981.
He won the Daily News' George Fencl Award in 1998 for reducing violent crime in the 25th District. Over the years, he served as the head of the department's public-affairs unit and the Internal Affairs Bureau. He recently oversaw the Police Academy and the radio communications room.
"I'll always love the Philadelphia Police Department," Colarulo said last night. "As much as I'll miss Philadelphia, I'm really looking forward to forging new relationships with the people of Radnor Township."
Zienkowski said Colarulo will take control of Radnor's 41-member police department on March 14.