Today HAB demobilized their equipment form the Moody Lake project work site and we are already preparing for our next project later this month in Burnsville, MN. There is no greater measure of success than safety and Moody Lake marks HAB’s 77th project without a safety incident. A special thanks to HAB’s Alum Transfer Specialist (Bernie Ruppert) for ensuring the our company Safety Plan is enforced and followed on all of our projects. This attention to detail and level of dedication is critical to successful applications.
This is the last of our daily postings, but check back soon (or receive automatic notifications by entering your email address below) for a posting of the final coverage map showing the location and rate of the alum application. Thanks for your interest and for following our progress. Don’t forget to check out HAB on Facebook, Twitter and Instagram too. Finally, a big thanks to the Moody Lake community, the Comfort Lake Forest Lake Watershed District and EOR for all of their interest and support. This support is also critical to successful projects. We have definitely enjoyed our time here and look forward to returning for future project phases!
Precise Alum Application
An important component of the successful Moody Lake project was the precise placement of alum floc on the lakebed. The floc is formed when the liquid alum mixes with lake water immediately after application. It is a whitish-green precipitant, is more dense than water and sinks through the water column at a rate of 1 foot every 2.5 minutes. Once it reaches the bottom, the floc’s active binding sites are in place to intercept phosphorus as it leaches from the lakebed.
HAB’s application technology maximizes the floc formation and settling by applying the alum through drop hoses that extend 18-24 inches into the lake. There are jet nozzles at the end of each hose and the alum is applied under the pressure created from the onboard pumps. This setup effectively injects a stream of alum that flash mixes with lake water below the surface. Floc immediately forms at a depth of 2-3 feet. Forming the floc below the lake surface bypasses any interference in settling by avoiding the surface tension of the water and algal scums on the surface. It also forms the floc at a depth where it is less susceptible to wave action. All of this results in rapid settling in the target application zone, reduces drift, ensures that lake sediments receive the prescribed dose without gaps in coverage and minimizes the time the floc is suspended in the water column.