Let me start with a couple of general principles. Then I'll pass the parole to Mr. Timlin.
Regardless of the age, the same level of safety is required for all pipelines. Any damage or deterioration of protection systems has to be monitored and remediated to provide the required continued level of reliability. We know that there are pipelines that are 60 years old and doing very well, because we're monitoring and making sure that they're performing as well as a pipeline that would have been installed last year. Realistically, however, we also know that aging infrastructure will appropriately require more attention than newer pipelines, so our measures take that into account.
I'll turn it to Mr. Timlin for greater detail.