We just completed this project last December. It was a fun and unique project. The Aeralater unit (removes iron and manganese) began to leak from the steel base plate about 3 years ago at a rate less than 1 gpm. The tank leaked as much as 30 gpm or about 20% of daily need prior to this project. It was cost prohibitive to correct this from the inside or by replacing the bottom section - cost range from $200k to $350k. So we came up with this "concrete curb/ring wall with chemical grout water stops" solution at a cost of $35k. The intent is to contain this until we can secure funding to replace the whole unit in about 5 years or so.
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Water Treatment Tank Repair - Unique and Successful Project
- Thread starter CrazyHorse81
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1. Do you really expect this repair to last 5 years? The interior corrosion is probably much worse than the exterior corrosion. While one can recognize that a lot of work was done, the repair work is in effect, just a bandaid until the tank can be replaced. Like putting lipstick on a pig.
2. There has been an emphasis in the last few years on upgrading water quality and operations at potable water treatment plants. It is typically recommended that the operating valves be automated. Automating the backwash valves improves the consistency of the backwash procedures with the result being an improvement in the filter effluent water quality
3. If this is a potable water application, how do you propose to disinfect the filter tank after the project is finished? You have existing holes in the tank that have not been repaired. You have an interior of the tank that is rusted and corroded. It will be difficult to insure adequate disinection. In addition, all of the repairs should have been made with NSF-61 approved materials that are suitable for contact with potable water.
4. The AERALATER has typically been sold in rural areas to uniformed engineers and rural communities. A knowledgeable engineer would have made sure that the AERALATER was fabricated from aluminum rather than steel. An AERALATER fabricated of painted steel will rust away and is difficult to repair and maintain because the small interior spaces are difficult to access for repairs and repainting. Unless requested, the seller also does not supply adequately sized manways which compounds the issues.
5. The repair estimate for replacing the bottom seems to be a little on the high side.
6. Thanks for posting this. Perhaps it may save someone from making the mistake of buying an AERALATER or one fabricated from steel. You should replace the tank with one fabricated from aluminum. The phrase that comes to mind: The bitterness of poor quality remains long after the sweetness of low price is forgotten.
2. There has been an emphasis in the last few years on upgrading water quality and operations at potable water treatment plants. It is typically recommended that the operating valves be automated. Automating the backwash valves improves the consistency of the backwash procedures with the result being an improvement in the filter effluent water quality
3. If this is a potable water application, how do you propose to disinfect the filter tank after the project is finished? You have existing holes in the tank that have not been repaired. You have an interior of the tank that is rusted and corroded. It will be difficult to insure adequate disinection. In addition, all of the repairs should have been made with NSF-61 approved materials that are suitable for contact with potable water.
4. The AERALATER has typically been sold in rural areas to uniformed engineers and rural communities. A knowledgeable engineer would have made sure that the AERALATER was fabricated from aluminum rather than steel. An AERALATER fabricated of painted steel will rust away and is difficult to repair and maintain because the small interior spaces are difficult to access for repairs and repainting. Unless requested, the seller also does not supply adequately sized manways which compounds the issues.
5. The repair estimate for replacing the bottom seems to be a little on the high side.
6. Thanks for posting this. Perhaps it may save someone from making the mistake of buying an AERALATER or one fabricated from steel. You should replace the tank with one fabricated from aluminum. The phrase that comes to mind: The bitterness of poor quality remains long after the sweetness of low price is forgotten.
- Thread starter
- #3
CrazyHorse81
Civil/Environmental
bimr
1. Only time will tell - it took three years for it to leak as bad as it did from the base. Now I expect it to creep up the tank wall and start leaking above the curb. We did patch welding to all the holes along the bottom 18" so it has to make it that height and then out.
2. Automation is good when you have a qualified operator, or even an operator staffed period. Certified operators aren't a reality in this area. Unfortunately, automation to some means set it and forget it. Also, with a 20 percent collection rate, the more controls, actuators, transducers etc. you have means more items to be replaced and before you know it they are operating in hand anyway.
3. It is potable water service. There are three chlorination points at this plant...one post detention/pre-filtration, one post filtration, and one post clear well. Disinfection would continue as normal once put back into service. All products used in the repair are NSF-61 approved for potable water (a challenge in itself) including the chemical grouts, foam cord, cement mix, dowel adhesive, and injection hose.
4. Yes, aluminum > steel...30+ year-old shoulda-woulda-coulda thing at this point. Yes, you can see in the photos that manways had to be cut in to gain access inside on a previous project.
5.
6. The Aeralater is performing well regarding iron and manganese removal, so I have no issues with that. It has performed very well over its lifetime as there is no iron or manganese build up in the distribution system. I do agree that whatever type of unit is selected to replace this one should be aluminum or other corrosion resistant material.
1. Only time will tell - it took three years for it to leak as bad as it did from the base. Now I expect it to creep up the tank wall and start leaking above the curb. We did patch welding to all the holes along the bottom 18" so it has to make it that height and then out.
2. Automation is good when you have a qualified operator, or even an operator staffed period. Certified operators aren't a reality in this area. Unfortunately, automation to some means set it and forget it. Also, with a 20 percent collection rate, the more controls, actuators, transducers etc. you have means more items to be replaced and before you know it they are operating in hand anyway.
3. It is potable water service. There are three chlorination points at this plant...one post detention/pre-filtration, one post filtration, and one post clear well. Disinfection would continue as normal once put back into service. All products used in the repair are NSF-61 approved for potable water (a challenge in itself) including the chemical grouts, foam cord, cement mix, dowel adhesive, and injection hose.
4. Yes, aluminum > steel...30+ year-old shoulda-woulda-coulda thing at this point. Yes, you can see in the photos that manways had to be cut in to gain access inside on a previous project.
5.
6. The Aeralater is performing well regarding iron and manganese removal, so I have no issues with that. It has performed very well over its lifetime as there is no iron or manganese build up in the distribution system. I do agree that whatever type of unit is selected to replace this one should be aluminum or other corrosion resistant material.
I do appreciate the issues that you have. Been there and done that.
I would suggest that you keep an open mind on the automation. Advances in control system technology have reduced the cost so much that control systems are quite affordable.
Recent articles have shown that automated backwashing systems significantly outperform systems with manual backwash procedures. It is a water quality issue, not an operating cost (labor) issue. I would never consider a manual backwash system especially for a water system of the size that you have. I am refering to a semi-automatic backwash system (operator initiated) sytem, the constrol systems does not have to automate the entire facility.
I would suggest that you keep an open mind on the automation. Advances in control system technology have reduced the cost so much that control systems are quite affordable.
Recent articles have shown that automated backwashing systems significantly outperform systems with manual backwash procedures. It is a water quality issue, not an operating cost (labor) issue. I would never consider a manual backwash system especially for a water system of the size that you have. I am refering to a semi-automatic backwash system (operator initiated) sytem, the constrol systems does not have to automate the entire facility.
- Thread starter
- #5
CrazyHorse81
Civil/Environmental
I will keep an open mind regarding automation. Our next step is to perform (at least one) pilot studies to evaluate the best replacement. It seems from touring other newer facilities the processes within the treatment system unit are, in-fact, automated.
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