Do Ontario One Call locate requests cost anything?

No, there is no fee. The Ontario Underground Infrastructure Notification System Act, 2012 states that no fee is charged to an excavator for submitting a locate request, and Ontario One Call's homeowner page confirms it is free.

Anyone who digs, bores, trenches, grades or excavates is an excavator under the Act, and that includes a homeowner digging their own footing holes. The requirement is to submit a locate request and wait for each affected utility member to respond before starting to dig. Members have five business days to respond.

The locate covers public underground infrastructure. Private lines on your property are a separate matter: you are responsible for having those marked yourself before digging begins. Private lines to think about include a gas line running to a barbecue or pool heater, electrical lines to a shed or detached garage, outdoor lighting or signs, sewer and septic piping, and telecom or electrical lines feeding security cameras.

If you hire a builder to do the digging, the obligation still applies. Ontario One Call's homeowner page says to make sure your contractor contacted Ontario One Call before starting. You can also submit the locate request yourself on their behalf.

One practical note: we found no published figure for how long a locate stays valid, so confirm that with Ontario One Call when you submit your request.

If your deck footings will require digging, submit your locate request through Ontario One Call before any work begins, and if the deck will be attached to the house or its walking surface will be more than 600 mm (24 in.) above grade, look into the building permit requirement with the City of Ottawa's Building Code Services at the same time.