Recently we were called out to Dingwall to effect repairs to the waste water treatment works that service the area.
The Works
Dingwall Wastewater Treatment Works are one of many in the region that were constructed in the early 1980’s and are owned and operated by Scottish Water.
The Dingwall plant accepts waste from a network of underground sewers and road tankers that collect from a wide range of septic tanks all around the region. The waste goes through various stages of treatment at the plant.
The first stage of this process involves the waste being fed into two Primary Sewage Treatment tanks (PSTs). These are large circular tanks with concrete floors and walls designed to contain the waste for treatment. The waste is skimmed to remove solids. The remaining liquid is then filtered and fed into a mechanical maceration process.
This mechanical “skimming process” is achieved through use of a rotating arm that is centrally mounted on the PST. The arm of the “skimmer” runs on an electrically-driven wheel on top of the concrete walls around the perimeter of the tank.
However, the action of the electrically-driven wheel rotating for 24 hours a day, 365 days of the year has a damaging effect on the top of the concrete wall. As the wall degrades, the wheel is prevented from functioning properly, invariably causing the rotating skimmer arm to stop.
At this point specialist contractor, MA Ventures Ltd were called upon to effect repairs.
What We Did
In this most recent instance, three tanks needed urgent treatment.
The first step was to drain the tanks and mechanically remove the defective concrete.
The tops of the walls are then reinstated. We did this by erecting carefully levelled, curved formwork. We used laser technology for this levelling process to re-establish the walls at the exact level necessary to allow the rotating skimmer arm to run at the original operating line and level.
Once the formwork was in place, specialist fast-setting, high-strength concrete products were used to build up the wall to the required level. When the build-up had cured, the final concrete was put in place. This material was again a high-strength and durable concrete product. Once hardened and sealed, it produced a long-lasting surface for the skimmer wheel to run on.
Unsung Heroes
The work of MA Ventures was vitally important to ensure the works could continue to function at its full efficiency, but the true unsung heroes are the operatives who operate these plants. They deal with the collection, treatment and disposal of the region’s waste water on a daily basis. Their work in operating and maintaining the treatment plant ensures our waste water is recycled to a quality at which it can enter back into the environment.
Without the hard work of the Scottish Water staff at Dingwall Wastewater Treatment Works, we would not have the clean environment we all enjoy today.
Neil Cowper – Project Manager for Scottish Water said “May I take this opportunity to thank MAV in undertaking and completing this scope of works, the quality of the work and the manner in which it was carried out.”
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