Riley Kooh | June 16th, 2022
Water is the single most important resource for supporting communities around the globe. Whether it’s for residential, industrial, municipal, or commercial use, water is used in countless ways, many of which we rarely actually see. The United States alone uses 327 billion gallons of surface water every day. But where does this water come from?
An enormous amount of usable surface water is kept in water storage tanks. In North America, the market for water storage systems is estimated at $US 3.4 billion and expected to grow to $US 4.1 billion by 2024 . Inspecting these tanks is imperative for structurally sound, clean and safe water for power, agriculture, mining, and household use. Without routine inspections, issues can arise quickly and sediment can build, compromising the integrity and cleanliness of the water.
Fiberglass tanks can be installed both above ground and underground. Underground installation allows for a large amount of water storage, without affecting the usability of the ground topside. These tanks can be completely covered, using a manhole style access point for inspections.
Concrete tanks can be molded to countless shapes depending on the project, and typically last up to 50 years with proper maintenance. However, once degradation sets in, concrete is prone to cracking and has a relatively complex repair process. These tanks are popular permanent storage systems for potable water, rainwater, stormwater, or sewage.
Beyond the tank itself, potable water tank inspections are crucial for good water maintenance. Over time, sediment can gather and collect along the bottom of tanks. If in small amounts, sediment has no impact on the quality of the water or on the structural integrity of the storage tank.
However, over time as that sediment builds up and mixes into thicker ‘sludge’ material, issues begin to arise. These negative effects can result in health concerns for potable water, or tank material degradation from the concentrated substances. Tank manufacturers generally recommend a minimum of one inspection and subsequent cleaning per annum. This is to ensure long-term integrity, extend the tank life, and avoid costly repairs.
At any reasonable time, an officer can conduct an inspection to ensure that stored water is abiding by safety standards. As a general rule, it is recommended that water tanks should be inspected and cleaned at a minimum of once every six months for drinking water and once a year for non-potable water.
Empty The Tank for Entry To allow for workers to enter and begin cleaning the tank, it must first be completely emptied of its water contents. Ensure that the water is drained into the ground away from plants for safe, legal disposal. All workers must be certified for working in enclosed spaces.
Clean & Rinse Once emptied, workers can vacuum out any sediment, scrub the interior with a detergent, and pressure-wash rinse the interior until all traces of detergent are gone.
Disinfect Depending on the size of the tank, a calculated ratio of water and chlorine-bleach should be added and allowed to sit for a minimum of 4 hours to disinfect the tank.
Drain & Refill Once disinfected, workers can drain the tank again of the chlorine-bleach solution and refill with clean water.
Test & Repeat if Necessary To ensure that chemical levels are safe for human use after cleaning, workers should test water samples and repeat the drain and refill process if necessary.
This method can be extremely labor intensive and costly. While conducting a dry inspection and cleanout, the water tank must be completely taken out of service. This means that alternative water supply must be implemented to prevent shortages and can be logistically or economically challenging. This method also puts workers in potential danger working in confined spaces while handling chemicals. Additionally, cross contamination is always a concern whenever humans enter the tank, even if all precautions are taken.
Talk to us about how our ROVs improve the safety, cost and speed of water tank inspections and cleanings
The most notable benefit of this over dry cleaning is the ability to maintain water in the tank. Dewatering can waste thousands of gallons of water and can sideline water supplies for multiple days. However, some negative considerations of divers are the cost, risk, and time consumption.
Due to the complexity of performing submerged tasks, commercial divers undergo rigorous certification, which reflects in high hourly cost. Additionally, the associated dangers of diving in confined spaces with single exits puts divers at risk and can increase the risk premiums. Divers are also limited to their gas supply, meaning frequent resurfacing which can extend cleaning times. While proper sanitation should always be performed pre-entry, having divers directly enter the water does carry the risk of cross contamination as well.
The disinfection process is much simpler for an ROV in comparison to humans, and can be done by simply soaking or spraying the vehicle with a solution. Thanks to extended battery lifes, cleanings can be completed quickly with zero or minimal breaks. Since the operator can remain topside, there is no risk associated with diving or entering confined spaces, and all imperfections can be easily recorded and used for asset monitoring.
For an example, we look to Ron Perrin Water Technologies. Previously, they would drain a 110ft standpipe of up to 100,000 gallons of usable water in order to clean the tank interior. After purchasing a DT640 VAC from Deep Trekker, they were able to accomplish this quicker and easier, while wasting zero water.
For testimonial, we look to The Tank Inspectors, a 30-year established water tank service and installation company. After purchasing a DT640, Operations Manager Jo Hulands noted that where the team used to have to put a diver in the water, they can now use the ROV. “Pretty much 80% of the tanks that we do we can clean with the vacuum cleaner”.
By using the ROV in lieu of a human diver, The Tank Inspectors not only keep humans safe but save time and money. In addition to OH&S standards regarding people in tanks and limiting the time people can actually be in the tanks, Dan noted that with the ROV “there’s a lot less set up time, divers require a lot of set up.” Furthermore, the divers require scheduling and coordinating where the DT640 can be deployed quickly and conveniently.
In addition, the use of the DT640 saves the Tank Inspector team significant amounts of money, estimating that the ROV is “40% of the cost of using divers.” “In fact,” Jo continued, “many diving companies themselves use the ROV to limit dive time by scoping out jobs with the DTG3 and undertaking cleans with the DT640.”
Check out the full case study here.
The DT640 VAC Being Sprayed with Disinfectant
For a Deep Trekker vehicle, disinfection is simple and reliable, thanks to their compact and intuitive design. To disinfect, simply spread the vehicle and tether on a clean and disinfected ground sheet. Then, thoroughly spray down materials with a chlorine-bleach disinfection solution. Alternatively, the vehicle and tether can also be soaked in the solution. Note that all plastic ropes and cables, used to hoist a vehicle for example, must be treated in the same manner.
The handheld controller and tether system are also designed with portability in mind. Replacing large control consoles and bulky tether is essential for maneuverability. The included tether utilizes a polyurethane outer jacket with embedded synthetic fibers to achieve a 200lbs working strength at under ¼ inch diameter to fit on a compact reel system. The combination of controller, tether, and battery powered vehicle simplifies working at heights and provides superior portability between jobs.
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