Lake Bank Project Explained

In early July the Grounds Department began working on a lake bank stabilization project. It's no secret that our 40-year-old lakes have eroded severely in many locations. One of the most significant areas of erosion was along the lake shared by numbers 12 and 16. This also happens to be our largest lake. I took a great deal of time over the past year to investigate the options for stabilization as well as reclamation of what has eroded. While we've built some nice walls in the past, it was unfeasible and cost prohibitive to build walls around each lake. We could have simply hauled fill to the lakes and dumped it in to reclaim the shoreline, but this process would be extremely time consuming, hazardous to the golf course due to repetitive equipment traffic and disruptive to golfers. Simply backfilling would also tend to be a short-term fix as that soil would still be susceptible to erosion. We also looked at using rip-rap or rocks to line each lake which would help with future erosion but still had the issues of damaging the golf course through hauling and being disruptive to golfers. The most cost effective, time efficient, environmentally friendly, least disruptive to golfers and long lasting solution was the use of geotubes. 

A geotube is a large bag made from a high-strength, permeable, synthetic textile. The geotubes we are using are 300 feet long with a circumference of 14 feet. The geotubes are postitioned inside the lake at the location where the new water's edge is to be. In some instances the geotubes are right along the shoreline. In other instances they are several feet out allowing us to move the shoreline 15-20 feet. This makes the lake smaller and the fairways wider! 

Once the geotube is positioned our workers pump sediment off the bottom of the lake and into the geotube. Seems logical to use this sediment since it used to be the old lake bank until it eroded. As the geotube fills with a sediment solution, the water pushes through the permeable textile leaving only sediment inside the tube. The tube rests on the bottom of the lake and will serve as a barrier to keep loose soil from being washed away into the lake. The geotube is filled with sediment until it is slightly above the water's normal elevation. 

   Chris stands on a dredge barge selectively pumping

   sediment into the geotube while Pedro and Jack assist

   

We currently are down to the last 150 feet of Geotube needing to be filled to serve as a protective barrier along number 12. At that point, additional sediment will be pumped between the old shoreline and the geotube. 

   Jack is pumping sediment between a geotube and old shoreline

Once the void is filled between the bottom geotube and the old shoreline a second bag of cheaper material is placed on top of the first bag. Once full, this bag will be cut open and the sediment inside will be used as grading material to create a nice, smooth slope from the existing grade down to the water's edge covering the bottom geotube. At this point the slope will be sodded and project complete. The series of illustrations below help describe the remaining steps.

   

It's difficult to predict a time of completion for this project as we are experiencing a learning curve. I am happy to say that we accomplished the same amount in the last three weeks as what took us the first two months. This is due to us making adjustments as the process rolls out in order to increase efficiency. Once the bottom geotube is complete all the way to the wall on number 12 we will begin working backwards from that point towards 16. Instead of completing all of the fill and 2nd geotube prior to grading and sodding, we will systematically work in stages to complete 12 fairway and 16 fairway in order to have those areas ready for play ASAP. Until then, these areas are marked as Ground Under Repair to the water's edge. (Sorry, if your ball goes in the middle of the lake you do not get a free drop) This is for your safety. There are numerous stakes and ropes that can be tripping hazards. 

I hope this sheds some light as to what we are up to. Once complete, we should have a very nice finished product in terms of both appearance and stability. I will continue to provide updates in the coming weeks including the plans for re-grading and widening16 fairway. Stay tuned!