His trial will commence on May 14, 2016
The county official was freed after he denied charges of corruptly giving a benefit and that of conspiracy to commit a felony.
Wainaina who appeared before Anti-Corruption Magistrate Felix Kombo denied corruptly offering Sh1 million to Nairobi Senator Mike Sonko as an inducement not to pursue a case in which senior officers are allegedly constructing private property using public funds.
The corruption offences were allegedly committed on January 5, 2016 at the Kenyatta International Convention Centre (KICC).
Wainaina is alleged to have corruptly given the politician the money through his secretary, Roseline Oluoch, who was charged last week.
She also denied the claims and is out on bail.