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LAKE ELMO CITY COUNCIL MLETING, OCTOBER. 219 1980 -7- LITTLE SUNFISH HEARING: Engineer Bohrer estimates 125 acre feet need to be removed or stored, Jess Mottaz asked if ground water or run-off is responsible for flooding, Engineer Bohrer replied both affect the lake; but, he does not know which is the predominant factor. Records from Valley Branch, piezometer readings by Cimarron and TKDA all locate the ground water table within 1-2 feet of each others reading. This indicates that 6 feet or so can be removed from Little Sunfish before getting into the ground water table. If six feet are removed, the Engineer said the plant would be almost 100•1 safe. Steven Taylor, Cimarron, asked if there was an over -flow would 6 .feet still have to be removed from Little Sunfish to get the same results? Dagineer Bohrer said no, Steven Taylor asked how much would have to be removed with, over --flow? Ehgineer Bohrer said an over -flow would have to be installed a few feet lower than the present water surface of 879. If this type of over -flow is allowed, it would have to be a valved type similar to Beutel Pond, that could be opened and closed as necessary, Councilman Morgan noted that somewhere between 0 and 125 ft, would help. Engineer Bohrer said you would get some help by diking, somemore by transferring into other potholes. is estimate of 125 acre feet includes water that is in Little Sunfish and some estimate of bank storage that will, seep out as the water is being removed, but no recycling of any ground water. Councilman Mottaz asked .for a clarification of the Board of Managers decision that, even though we are'faced'with a good possibility (90&/) of having to close Cimarron Park, they would not give the City a permit to pump out 125-acre feet into an area that is not flowing out. It will not ad.d to the elevation of Horseshoe Lake nor the rate the water is flowing out. Would you (VBW.D) rather the City take the risk of losing sewer for 25% of the pipulation of Lake IRmo next spring than to authorize the City or give up permission to pump out 125 acre feet? George Hedges - Larry Bohrer said we have flooding problems downstream already and, VBWD would like to see everything else possible done before we start passing off water. Engineer Bohrer went on to say that the general lay of Cimarron's property is not conducive to pending. There are no natural depressions. In his opinion, one would have to make a depression by making a :dike or ex- cavating. Another possibility is to split Little Sunfish Lake in half at County Road. 70 by blocking the connecting culvert, which is submerged. He had approached the County with the possibility of plugging this large culvert, installing a small culvert at a higher elevation to protect their roadbed (they would not allow anything that would. saturate their subgrade) and then pump some of the water from the south side to the north side. This would increase the level of the north side about four feet. The water would encroach onto some property that it is not encroaching on now: Tartan Meadows Subdivision. And, it would, jeopardize the gravel driveway to the farmsted at Tartan Park. The gravel driveway would have to be relocated - probably across Paul Emerson's property, if he would agree. The County would not give the Ilhgineer a firm answer. They recom- mended sumitting a permit application for consideration. Administrator Whittaker asked the cost of this vs pumping. Bohrer does not have an accurate cost analysis; but estimated pumping 125 acre feet would be $109800 and pumping half the amount could be about half the cost regardless of where it is pumped. Additional costs would be in installing the culvert across County 70. This cost could be about $1,000 if the County allows the City to open -cut the County road. Generally, however, they require augering underneath the road. This operation would be at least as expensive as Alternate 2 ($109800),