Water storage tank inspection and maintenance 101
Rachel Doornekamp | February 22, 2021
Why Clean and Inspect Water Tanks?
Tank inspection is imperative for structurally sound, clean and safe water tanks. Without inspections, issues can arise quickly and sludge can build, compromising the integrity and cleanliness of the tank.
Being on top of your assets will allow you to prioritize repair and replacement schedules. Many tank manufacturers offer warranties and having tanks inspected are typically needed to keep up with the warranty.
Effective inspection and cleaning is crucial for good water maintenance. Over time, sediment sinks to the bottom. Even your drinking water has some particles and minerals in it. Small amounts of sediment have no impact on the quality of the water or the health of those who drink it, it also has next to zero impact on the structural integrity of the storage tank. However, over time as that sediment builds up and mixes into thicker sludge material, it can have impacts on the water quality and on the structure of the tank. Any tank manufacturer recommends regular water tower inspections and subsequent cleaning of the tanks to ensure long-term integrity, extend the tank life and avoid costly repairs. Read on for our step by step guide to basic tank inspection and cleaning with Deep Trekker vehicles such at the DT640 VAC, DTG3, and DT640 MAX.
Advantages of Using ROVs for Tank Inspection and Cleaning
The advantages of using underwater vehicles for tank inspection are numerous, with the overall benefit of saving time and money.
Minimize Time Required
The use of an ROV for tank inspection and cleaning significantly minimizes the time needed to complete the work. With quick deployment time, a vehicle can be deployed in minutes to get eyes underwater immediately. Without the need to schedule and coordinate with divers, work can be done quickly and efficiently. Dan Hulands of The Tank Inspectors shared that with the ROV “there’s a lot less set up time, divers require a lot of set up.” Dan also went on to observe that, “the divers know about diving - they don’t necessarily know about tanks. All of our operators know about tanks and have been working with tanks for many years.” With the ROV, tank experts can get their eyes underwater to conduct specialized inspections and cleaning.
Furthermore the portability of battery powered crawlers and ROVs allow for vehicles to be conveniently transported to a variety of locations within the same day - without the hassle of an external power source. Jeff Conway from the City of Independence noted, “Having a battery powered camera lets us take these vehicles wherever we need without the need of a generator for power.”
Maximize Cost Effectiveness
By eliminating the need for divers, the use of submersible robotics allows teams to reduce their tank cleaning and inspection costs. Dive teams do not need to be hired every time a tank needs to be looked at, allowing teams to save significant amounts of money. Additionally, the deployment and operation of an ROV or crawler only requires one to two employees.
Perhaps most importantly, tanks can be kept in service and do not need to be drained in order to complete the job. Robert Perrin of Ron Perrin Water Technologies shared the convenience of using the Deep Trekker DT640 for standpipe cleaning. “We use the vehicle instead of divers for tank cleaning,” he said. “Before we got the vehicle we would have to drain the tanks and the utility would lose up to 100,000 of gallons of water.” Michael McAloon, PE, Water/Wastewater Department Manager with Suburban Consulting Engineers echoed this statement, “The Deep Trekker is critical in providing inspection and condition assessment of water storage tank interiors, while maintaining normal system operations.”
Increase Safety on the Job
The use of a vehicle eliminates the safety risks associated with divers. With a submersible, human beings aren’t required to enter any confined spaces or risky situations. The battery powered vehicle also limits contamination risk. Because you don’t need generators or other external power sources, Deep Trekker’s ROVs are not only convenient, they reduce the risk of spilling fuel or contamination. Finally ROVs and crawlers are light and portable, making them safe for staff to transport and handle.
Camera equipped vehicles allow teams to provide detailed inspection videos, photos and reports on their work. Teams can provide clients with professional and thorough documentation of their work. “The ROV is critical in assisting SCE with gathering the necessary information to identify tank deficiencies and problem areas. This information gathered is crucial in our report recommendation for appropriate rehabilitation measures, following tank inspection,” shared McAloon.
How to Clean and Inspect Water Tanks
Inspect Equipment and Prepare Pump
To start, users should first open their Pelican case and ensure that they have everything they need for the job. It is important that vehicles are given a quick once over to confirm that all required parts are intact and ready for use.
Next the topside pump for the DT640 VAC should be connected and prepared.
Prior to putting the vehicle into the water it should be thoroughly cleaned to ensure safety and cleanliness for potable water sources.
The benefit of using a vehicle for tank inspection and cleaning is the ease in which the robot can be cleaned. One of the major risks associated with sending divers into tanks is the risk of contamination from their equipment if they do not follow a strict procedure. There are a lot of “nooks and crannies” on a dive suit that can hold bacteria and other potentially harmful materials to the potable water. “It’s nice to save my divers from unneeded climbing or entry into a tank that was in good shape,” Mountain West Commercial Diving’s Jake Spaulding adds, “It is so much nicer to hoist the ROV to the top of a tower than it is to send a diver dressed in up a 65 ft ladder. Now we only send in divers if we know what is needed.”
Vehicles and tethers can be cleaned with a hypochloride solution. This procedure is outlined in our Step by Step Guide to Cleaning ROVs for Potable Water Services.
Start Pump and Clear Out Sediment
Once the vehicle has been cleaned and connected to the pump cleaning can begin. Using the lifting hook and rope, the vehicle can be safely lowered into the tank and the pump can be turned on.
Using the handheld controller, operators can drive the vehicle on the tank floor to effectively and efficiently clean sludge.
Once the tank has been thoroughly cleaned, it can be inspected to ensure structural integrity. The use of remotely operated vehicles such as the DTG3 is a safe and convenient method for conducting accurate and complete inspections.
The ROV can be driven around the tank to get a close up view of tank walls and floors and roof. Furthermore, video and images can be captured to document any potential issues.
The HD camera and straightforward navigation allows users to get a complete picture of their tank. ROV tank inspection provides users with a convenient and safe way to ensure tank integrity.
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