3.A guard or peace officer,
(a) may require any person entering or attempting to enter any public work or any approach thereto to furnish his or her name and address, to identify himself or herself and to state the purpose for which he or she desires to enter the public work, in writing or otherwise;
(b) may search, without warrant, any person entering or attempting to enter a public work or a vehicle in the charge or under the control of any such person or which has recently been or is suspected of having been in the charge or under the control of any such person or in which any such person is a passenger; and
(c) may refuse permission to any person to enter a public work and use such force as is necessary to prevent any such person from so entering. R.S.O. 1990, c. P.55, s. 3.
The way I read the above--bolded text mine, and important--Chief Blair's wrong: since the site was declared a "public work", albeit in secret, his force is in the clear. I'm not sure what's more disturbing, actually: that police can, without warrant, arrest and search somebody simply for being too close to "a public work"...or that Blair didn't know this...or that not knowing this, he instructed his police to act as if he did.