The part of the sentence 'where he participated' is correct and usable in written English.
You can use it to refer to a location or event where someone has taken part. For example: John attended a conference in London, where he participated in several workshops.
His reintegration process began in earnest during the Lord's Test, though, where he participated in practice sessions.
His first mission last October took him to the International Space Station, where he participated in three spacewalks.
(Last week, Mayor Paes attended a TED conference in Long Beach, Calif., where he participated in a panel about cities).
Davidson studied at the University of Edinburgh (1835 36) and on the Continent, where he participated in several geologic tours.
Soon thereafter he left for Greece, where he participated in the Greek War of Independence against the Ottoman Empire.
He worked at Boeing in Seattle from 1951 to 1955, where he participated in the design of the Boeing 707, the first commercially successful jet airliner.
That is what Mr. Hirai had learned at the Japan Federation of Bar Association, where he participated in efforts to send lawyers to the hinterlands.
I am the father of a 22-year-old Navy corpsman who has just returned from Baghdad, where he participated in the initial invasion.
He is well known to German audiences and has also won a following in London, where he participated in the BBC's New Generation Artists program.
The news conference was held on the general's return from Washington, where he participated in a wide-ranging review of war strategy in Afghanistan.
Both Laney and Miss Baby become romantically involved with Lester Stipp, an inscrutable veteran of the Iraq war, where he participated in a horrifying war crime.
