Dam Committee LTPOA Summary for July 8, 2008

Mo DNR dam safety engineers Glenn Lloyd and Paul Simon visited the dam on Monday June 30, 2008 for its triennial inspection. (Last inspection was in Apr 2005.)
 
The inspection went well with only a few minor "to do" items on the list:
1) Finish cutting the back of the dam. (The dam was only about one third cut when the inspectors showed up. It needs to be finished.) It is done now.
2) The bushes remaining on the face of the dam need to be removed. (These are mostly Button bush and Redbud along the shoreline. Glenn recommended cutting them off flush and coating the cut trunks with polyurethane varnish to ensure that they do not grow back. The danger of bushes and trees at the water's edge is that they provide cover for burrowing animals like muskrat, which can undermine the dam. The rip-rap also discourages burrowing animals.
 
Whether or not the dam passes inspection will also depend on the "downstream" survey. Our dam is a class 2 dam, since at the 2005 inspection there were 8 houses downstream of the dam. If the inspectors now find 10 or more houses downstream, the dam will be reclassified as a class 1 dam. This would require increasing the height of the dam or increasing the capacity of the spillway or both. Hopefully, the inspectors will not discover any new dwellings downstream. (If the need does arise to increase the height of the dam, it is unlikely that fill could simply be added to the top of the dam. This is because the back of the dam is too steep to support the added weight. So in addition to adding to the top of the dam, the back of the dam would also likely have to be built up.)
 
Other items:
 
1) I still have to write up the request to make the siphon permanent.
2) The inspectors very strongly recommended that the back of the dam be cut (or burned) twice a year. They suggested using a track bobcat for a dam as steep as ours. They also suggested not cutting the dam too short for a steep dam.
3) The inspectors suggested a lock on the gate to limit access to the dam area (exclude ATVs, etc.).
4) The seepage drain is a 12 inch pipe supported by concrete blocks and 2x6 wood blocks. Inspectors suggested a more permanent support, something less easily tampered with. Alternatively, the pipe added to install the weir can be removed. As long as the leak remains a trickle the flow rate of the leak does not have to be measured. 
5) I asked about a road over the dam to access a sewer treatment plant built behind the dam. Glenn said a road would not be a problem, but the road surface would need to be improved (asphalt or rock) and a permit may be required. (Permits from Dam Safety are fast and free at this time.)
6) Paul spotted some cattails on the north abutment that I have not seen before. After the dam is cut I will determine if the cattails are due to runoff or seepage and try to gauge the seepage.
7) Inspectors were satisfied with the repair work done by Dave Taylor.
 
Rich Hirsch for the dam committee.