Water Tank Inspection Best Practices with an Underwater ROV

Viewing water tank inspection best practices with an underwater ROV (remotely operated vehicle) or underwater drone. Cities, municipalities, and contractors are using these underwater camera to document the condition of the tank and for any security issues - without shutting off services.

---

Water Tank Inspections for Safe Drinking Water

Safe drinking water may be something we take for granted here in Canada, but behind the scenes what we may not realize is that a lot of time and money is put in to ensure this continues, especially as our urban populations increase. Reservoirs, water towers, and pipelines alike all play a major part in the water coming out of your tap. These systems all are required to be inspected regularly to ensure no harmful bacteria enter our homes. Case Study: Monterrey Tank & Reservoir Repairs with Deep Trekker

Conventional Water Tank Inspection

Traditionally, divers were required to complete the inspections – but with diver safety a large priority, inspecting these tanks regularly is costly and cumbersome. If you are like many of our customers, you may be considering switching to a micro ROV like the Deep Trekker DTG3 for your inspections.

ROV Water Tank Inspection

Are you ready to start inspecting multiple water tanks a day? With less than a minute of setup, you can start completing more inspections now with the Deep Trekker DTG3 ROV systems.

To get you started, we have put together this list of some things to keep an eye out for during your inspections.

Sanitary Conditions:

The construction of water towers and water storage facilities are designed to minimize the potential for contaminants entering the water. Even with these protocols, it is essential to first examine the sanitary conditions of the tank and fix any potential issues as soon as possible.

1. Ensure no insects, etc. have fallen into the storage facility
Many of our customers use the Deep Trekker grabber arm to retrieve these contaminants so they can be removed as soon as possible during regular inspections.
2. Inspect the roof and side walls to ensuring it is water tight with no openings. Inspect the brackets connecting overflow piping to the structure to assure they are secure to both the structure and the overflow pipe and that they are not damaged by corrosion.

Using the 270-degree rotation of the camera, conduct quick sweeps of the roof and walls of the tank can be completed with ease.

3. Roof access hatches should be checked to assure proper operation and fit, check if the roofs is well drained and do not tend to hold water.

Inspecting the outside of the tank is just as important as the inside. Luckily taking a look at the exterior of the tanks is pretty simple while you’re up there doing your internal inspection with the Deep Trekker ROV.

4. Confirm if silt is collecting in the bottom of a tank bowl, and how much. The deposits must be removed periodically to prevent microbial growths, to minimize corrosion and to prevent the deposits from going into the distribution system.

Many tanks will develop silt at the bottom, what is important is that it is managed to ensure it does not build up to start mixing with the water. Luckily with the Deep Trekker patented pitching system, instead of having a top or bottom thruster that would disturb the silt as you fly away from the bottom, the body and thrusters can be rotated away so not to disturb any silt throughout your inspection.

Structural Conditions:

This is where the Deep Trekker DTG3 ROV shines. With its small size it can fit into areas too small or dangerous for divers to go. The 270 degree rotating camera with LED flood lights can efficiently inspect all areas of the interior and intricate areas of the tank.

Below is a short list of areas to thoroughly inspect with the Deep Trekker DTG3 ROV.

1. Check the entire structure for water leaks including all manways, risers and tower legs.

The high definition and bright LED flood light illuminate your investigation areas even in the dark water tanks. Efficiently inspect the integrity of the entire system, with optional thickness gauge or laser scaler.

2. Confirm the anchor bolts haven’t rusted enough to materially reduce their strength. Ensure no dirt, grass or weeds have accumulated on the anchor bolts.

3. Check all welds and seams for cracks.

The laser scaler is an ideal tool for cracks, rust, and sediment to estimate size. Two lasers are positioned 25 mm apart above the camera, displaying on your handheld controller. With these reference points if issues of cracks or rust are found you can document the severity.

4. Check all bolts and rivets for corrosion and leaks.

Coating System Conditions:

Investigating the coating is an extremely important step to inspecting your water storage facility. The regulations and certification surrounding coatings inspections much more clear than general water tank inspections. We’ve outlined here just a few areas that you can inspect with the Deep Trekker ROVs.

1. If rusting is continuous, approximate the percent of the rusted area and determine the character of the areas (loose paint, blotchy, general corrosion, no paint). Determine the extent, nature, and depth of pitting.

Another example where the Deep Trekker camera and laser scalers come in handy. With the digital video recorder, all of this evidence can be easily attached to your reports.

2. Concrete structures should be inspected for signs of concrete deterioration (Spalding, cracking, leaking, etc.).
3. Glass coated structures should be inspected for cracking, corrosion and other signs of coating deterioration.

Safety Conditions:

With the Deep Trekker ROV, no topside power is required, so you can complete your entire inspection from the top of the water tower if you so desire. Often times, these water tanks are very high – your safety is extremely important.

1. Check ladder brackets to assure that enough is provided, that they are not damaged by corrosion and that they are secured to both the structure and the ladders.
2. Check the condition of all landings and catwalks to make sure they are clean, that they drain properly and are not damaged by corrosion.

Security Issues:

1. Access to water storage structures must be restricted to authorized personnel. Check to see that security fences are sound and that their gates and locks work properly, exterior ladders must terminate at least eight feet above the ground.
2. Check to see that all doors and access hatches are locked.

Why Perform a Water Tank Inspection with an ROV?

ROVs have the potential to improve the traditional approaches taken to water tank inspections. Our team has encountered the following benefits of using ROVs compared to traditional methods:

1. Using an ROV removes the risks associated with confined space entry, which requires permits, planning and paperwork.
2. Water tanks do not require discharging or refilling to perform ROV inspections.
3. Following an ROV inspection, if remedial works are needed, the footage can be kept and drawn upon, which can help to inform better planning in the future. This can save time and costs in the long-term.
4. ROV footage offers the kind of detailed, close-up views necessary to inspect a tank’s internal condition.
5. Deep Trekker ROVs have enhanced features and attachments that can gather samples from the inside of a tank and measure wall thickness.

Easily bring the Deep Trekker ROV up to the top of the tower with you or hoist it up the side. With no generator required, you can complete all of your inspections from the launch site on top of the tower – or still remotely from your inspection vehicle if you prefer. The digital video recorder will document your entire dive, including the depth, water temperature, and heading (applicable to the DTG3 Smart and Expert packages) to give directly to your client or to attach as documentation with your final report. Every county may have different requirements for proper water tank inspection, we hope that this short blog gives you a starting point to understand how you can ensure proper and safe inspections of our water storage facilities. Whether you are a municipality, private inspection company, someone wanting to start an inspection company, or just someone interested in investigating underwater mini ROVs like the Deep Trekker DTG3 provide unmatched maneuverability and will save you time and money.

US Underwater Services has utilized the DTG3 ROV for over 190 inspections during the last six months. -Jim Schrader, US Underwater Services

Interested in a Micro ROV for water tank inspection?Request a Quote today.

Finish the water tank inspection? Time to start cleaning ROV to clean your water tank!