The three main aspects of good wet weather friction are geometry (crossfall, gradient), macrotexture, and microtexture. The matter is complex and a systematic approach demands all three aspects receive attention. It can be likened to the legs of a 3-legged stool - if one leg is missing, the stool is unstable. Just what the facts are at Ottawa, I don’t know. But the Embraer 135 overrun at George South Africa in December was aquaplaning due to deficiencies in all three. The interim accident report is on the CAA website in South Africa:
AircraftAccidentReportsIndex
and look for the latest updates below the annual accident reports – 7 December 2009 ZS-SJW
decurion's comment about grooving presents a view that could be mis-interpreted. What Decurion says is not, in itself, incorrect:
A surface with large aggregate asphalt will have the same runway friction characteristics on wet/flooded surfaces as a grooved surface with the same average macrotexture
However the issue is that most asphalt surfaces have LESS macrotexture than a grooved surface, and crucially, less than the ICAO recommended minimum of 1.0mm. That is why, generally speaking, grooving makes a difference and an ungrooved asphalt runway is always looked at with suspicion that its macrotexture is below standard (unless or until proven otherwise).
Cheers
Overrun