Tailwater Recovery Ponds
Tailwater Recovery Ponds serve multiple functions, chief of which are surface water retention for secondary use, and water quality improvement. In some cases, an entire tailwater can be designed within the borders of one farm and as such can be designed upwards from the baseline elevation of the drainage in which it is built. In others, the drainage capacity of the creek cannot be altered because of concerns about backing water onto a neighbor’s land or impeding their drainage in some way. Our products can bring performance improvements in both cases.
Tailwaters built entirely on one farm are often designed such that they could be completely drained if they included a control device. Doing so would bring significant environmental benefits. The optimum timing of this drainage, or dewatering would normally be: 1) After a rain event that brought the tailwater to full pool; 2) after the farmer had been given ample opportunity to either use or transfer water to an onsite reservoir; 3) after enough time passed to allow settling of the tailwater to occur; and finally 4) before a second rain occurs. Point 4 is the big one. When a second rain enters a full tailwater it flows through the top like a river and takes its entire load of contaminants and top soils with it. Worse yet, turbulence tends to disturb a significant percentage of what settled out in the last rain event and takes that with it. So a second rain that encounters a full tailwater pool takes the entire contaminant load of the second rain plus part of what had been settled out before, thus negating much of the environmental benefit intended. The AutoRiser can solve this issue very simply. When the water level sensor registers higher than the gate position
it means a flood event is in progress. The AutoRiser counts time from the end of the flood event and after a predetermined amount of time has passed, it sets its gate slightly lower than the water level continuously, hereby dewatering the tailwater without negating its settling pond characteristics. Once the water is out it raises the gate back up so that the tailwater is to be ready to receive and settle out the next rain event.
Tailwaters that involve neighboring land are generally built differently. These are built below grade in the drainage and as such are more like bathtubs with no drain. Even so, with automation and programming these can be made to hold more water safely and to release excess water in a way consistent with their purpose of improving downstream water quality. Seasonally, water management objectives can change. Oftentimes in the summer months the focus is on irrigation and maximizing available surface water to apply to crops. In winter and other high moisture months the focus generally becomes removing water as quickly as possible. Our products can facilitate both objectives, while providing assurance that in the event of a large mid-summer rain event the gate will open to restore full drainage capacity to the ditch and thereby avoid contributing to any flooding that might occur on a neighbor’s fields.