Page 14 - Tennessee 811 Magazine 2022 Issue 3

Low Impact Verification:
By Jason Smith
with Maraliese Beveridge Colliers Engineering & Design
We LOVE LIV!
Utility designation and mark- out services are a cost- effective means of identifying potential conflicts with existing underground infrastructure, objects or utilities that need to be avoided during the excavation process. But how a locate is literally “marked- out” can make a big difference.
Some states have established policies around the concept of “low impact markings” that provide guidance for excavators on how to call in a ticket and for utilities responding to the ticket. According to Sunshine 811, the One Call service for Florida, “Whether requesting a new locate ticket or renewing an existing ticket, excavators are required to follow low impact marking practices. This begins with the locate description on your ticket. The practices [...] serve four purposes:
• Helps ensure the locate is accurate
• Reduces unnecessary locate marks
• Reduces the amount of time locate marks are refreshed
• Reduces time for the locator” We couldn’t agree more! Excessive Mark-outs
First, let’s begin with a mark-out observation that our technicians at Colliers Engineering & Design have encountered in the field. With millions of miles of buried utilities located beneath the surface of the earth and an abundance of new underground infrastructure being installed every day, that adds up to a lot of utilities. 811 One Call mark-outs are performed using electromagnetic detection which is a good first step. However, when a field technician uses excessive paint lines to mark-out a utility corridor, by adding more than what is standard,
it can hinder an excavation operation. Especially in urban sites with a high density of utilities.
Here’s Why
Let’s say the contractor is performing
a utility tie-in, in a congested urban setting. The site still has to be marked- out for all utilities. Assuming there could be up to 18 utilities under one location, and you’re only looking for the water line, you can see how excessive mark-outs are compounded by extreme marking. While it’s understood that
the tolerance on each side of the utility corridor is 24”, if the tolerance is also marked-out, it can become confusing when combined with all the other mark-outs, turning the site into a sea of paint lines. For example, if you have a 5ft utility corridor with a 24” tolerance on each side, the excavator will need
to dig a 9ft-wide trench. This work requires the contractor to hand-dig the site which increases the probability of injury as well as getting confused by excessive mark-outs which adds to the project timeline. Also in the mix is that if the contractor damages the utility, they’re responsible.
Meet SUE
So, now that you’ve seen the importance of Low Impact Marking, we’ve
taken that concept a step further by performing Low Impact Verification,
12 • Tennessee811 2022, Issue 3