Pittsburg Tank & Tower Group
Inspection via diver eliminates draining the tank, but introduce…
Mother Nature throws wrenches in the best-laid plans of even the best-run water utilities, and Kentucky’s Henderson County Water District (HCWD) is no exception. Seven tanks are professionally inspected every five years, but a tornado that touched down two blocks from a tank in fall 2013 torpedoed those plans. Rather than survey just that tank and the other six as scheduled the following fall, the board of directors approved inspections for all seven tanks that November.
Henderson County Water District
Profile: 6,400 customers in 475 square miles
Founded: 1964
Pipeline: 375 miles
Tanks: Seven (built 1966 to 1998)
Pump stations: Seven
Operating budget: $3.1 million
Employees: 11
Pete Conrad had come on board a few months earlier as supervisor. Instead of specifying dry inspection as the district had always done, he gave potential contractors the option to price dive, dry, or remotely operated vehicle (ROV) inspection. Pittsburg Tank & Tower Group (PTTG), which also is located in Henderson, submitted the lowest bid with an ROV – or underwater drone — inspection.
Divers circumvent the biggest hassle related to dry inspection — taking the tank out of service to drain it – but drones go a step further: They eliminate personnel safety issues related to submerging a human being for two hours to three hours. Someone must climb the tank to place the robot inside, an activity governed by the Occupational Safety and Health Administration (OSHA); but the inspection itself is conducted by an employee standing on the ground. A trained operator maneuvers the submerged drone using an LCD-equipped handheld controller.
“They’re like driving remote control cars except you can’t see the actual unit,” says PTTG Inspections Director David Haire. “You’re viewing everything on a screen.”
That’s one reason contractors with robots can charge less. The other is that they’re finished a little sooner. A diver would have to haul a bunch of gear up the tank. Plus, it’s easier to disinfect a 6-pound piece of equipment than a human being in a wet suit and oxygen tanks.
Conrad asked the board to approve the bid.
“It was a cost issue,” he says. “It was cheaper in the long run because we aren’t dumping water on the ground.”
Why ROV Assessment Costs Less
The American Water Works Association (AWWA) recommends inspecting potable water tanks every three years to five years. The National Fire Protection Association (NFPA) recommends tanks without cathodic protection be inspected every three years; tanks with it, every five years. Whatever the tank’s purpose, a full inspection scrutinizes the interior and exterior for problem areas or code violations. While the robot inspects the interior, crew members on the ground survey the exterior.
Conrad watched a drone inspection on a hot mid-July morning. When PTTG arrived, one crew member walked around the tank conducting ultrasonic thickness (UT) tests and paint thickness (MIL) tests. Another photographed the site, telemetry hut, tank, and accessories to verify tank height and diameter, manway size, ladder height, drains, and valve measurements. For example, because OSHA requires ladders to be at least 16 inches wide, a crew member photographs a teammate measuring the ladder. The contractor uses such photos to justify recommendations for improvements.
Once the picture taking and testing were complete, the drone was wiped with chlorine to avoid contaminating the water and lowered into the tank. After the inspection, the drone was once again disinfected with a chlorine solution, wiped down, and left to dry while cleanup was completed.
Customers usually receive a copy of the inspection report via e-mail within 14 days to 21 days, and a colored printed booklet of the report and DVD of the video within another week.
“We provide videos so customers can see exactly what we see during the inspection,” says Haire. “We take screenshots of the video to show specific elements within the interior for our reports, but letting the customer see the entire video proves you’re not hiding or exaggerating anything on the report and with your recommendations.”
Videos aren’t edited, so utility managers see everything as the drone recorded it. Videos are 5 minutes to 30 minutes long depending on tank size and type and number of pipes and accessories. The videos, which are archived in PTTG’s files, come in handy for future projects.
“We also do maintenance on the tanks and, sometimes, a customer calls and wants us to do work from a previous inspection two years ago,” Haire says. The company reviews its files and prices maintenance or repairs as requested.
Conrad deems inspection reports “super important.” Because they help him prioritize maintenance and repairs, they’re an invaluable annual budgeting aid.
“You can’t fix what you don’t know,” he says.
Code Violations
Only a few months on his new job as water superintendent in 2013, Conrad says he flipped out when PTTG returned several pages of recommendations after the first round of inspections. Since the contractor’s previous inspections found nothing amiss, he wondered why there were suddenly pages of code violations. Because regulations and standards constantly change, even a new tank can be non-compliant within a few years.
For instance, most of OSHA’s updated “General Industry Walking-Working Surfaces and Fall Protection Standards” went into effect in January 2017. Instead of mandating guardrails, the new rules expand an employer’s options for fall protection. However, some requirements – such as following construction scaffold standards instead of general industry standards – don’t become effective until mid-November 2018.
“That was a giant learning curve for me,” says Conrad. “I’m used to stuff where something is built and grandfathered in.”
It’s not uncommon to be cited after previous inspection reports found no or few deficiencies, so don’t feel overwhelmed if your utility is suddenly confronted with a list of violations. If a utility’s written a plan to address deficiencies, OSHA generally allows a year or two to come up to code – time enough to budget funds to address costlier issues. Conrad plans on addressing the district’s code violations a tank or two at a time.
Contractors: What To Look For
Municipalities and water utilities should keep a few points in mind when drafting a request for proposals, request for qualifications, or contracts for ROV tank inspection:
- Require experience with drone inspection
- Does the potential contractor employ an engineer who will be onsite to answer structural questions that may arise during inspection or review?
- Request video of a previous inspection so you know what to expect (blurry footage, for example, indicates lesser-quality drone)
- Request a sample report of an inspection
- Ask to watch an inspection before signing a contract
- Ask for referrals.
“Contact your inspection contractor because they can always explain things,” says Conrad. “It’s not as scary as people think and you’re not going to have a contamination issue. In the long run, it makes your inspection process a whole lot easier because it’s a lot less invasive than what’s been done in the past.”
