Dam Leak Committee Summary, Nov 14, 2006

Next meeting of the Dam Committee will be Sat. Nov 18 at 11 AM. Meet at the spillway near S Lakeshore Dr. We will try to locate some of the features referenced on the engineering drawing provided by Reitz & Jens and discuss where and how to install a weir box to measure the flow rate of water coming out of the leak. The dam and field behind the dam had been recently cut, so features normally obscured by weeds were more readily visible. If weather is poor on Sat., we will meet on Sun. Nov 19 at 11 AM instead.

On Nov. 11 Mike Leiweke, Kevin Seelbach and Rich Hirsch visited the leak pool on the north side of the dam. We were able to locate a 4 inch dia pipe to the right (south) of the main 12 inch pipe that comes from the seepage collector. This 4 inch pipe is on the Reitz & Jens drawing and is the outlet for the 250 foot drain pipe laid to the south of the leak pool at the toe of the dam. No significant flow appeared to be coming out of this 4 inch pipe.

The group felt that the best way to install the weir box would be to use a flexible connector to attach a new length of 12 inch pipe to the existing 12 inch drain that comes from the seepage collector. The new pipe would go thru an existing 20 ft x 24 inch dia pipe that runs under the haul road. The weir box would be placed in the creek on the downstream side of the road. Flow from the new 12 inch pipe would enter the weir box via a fitting on the front of the box or dump into the box from above.

In terms of constructing the weir, although it would be possible for Mike L. to construct a weir box out of stainless steel (donated by Ken Jost), the group felt it might be better to purchase a fiberglass box and for Mike to modify the box to hold the weir plate. A suitable fiberglass box costs about $750.

One problem is that the existing 20 ft x 24 inch dia. pipe running under the road is badly rusted and probably needs to be replaced before the weir box is installed. Kevin S. said he thought he could replace the rusted pipe with a plastic 20 ft x 24 inch dia pipe using a small excavator. The installation of the new pipe is complicated by the presence of flowing water. If needed we can divert the flow temporarily by using elbows and pipes into the field or over the field and back into the creek downstream of where the weir box will be located.

On Oct 15 M Leiweke, K Jost and R Hirsch visited the back of the dam. Their first stop was near the back of the Lake's property on the south side in the area where the seepage drain installed in 1982 should empty. There was quite a bit of foul-smelling water that had a layer of scum on top that looked like oil. The water present did not seem to be flowing or draining into the creek present at the back of the property. [By the way, there were two 5 inch diameter trees in this area had been cut down recently by beavers. There was no obvious dam, but we did not look hard.]

-- R Hirsch for the Committee