8.1. SR 07-18-2005
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JUL 1 5 2005
13065 Orono Parkway
Elk River, MN 55330
July 13, 2005
Mr. Bob Erickson
D.R. HortOn
20860 Kenbridge Court 11100
Lakeville MN 55046
RE: mOlT BROOK FARMS WETLAND
Dear Mr. Erickson:
nus correspo~dence is intended to give you a brief summary of past and recent events surrounding
the wetland complex in the Trott Brook Farms subdivision. In 1999/2000 when the City was
planning to extend urban services to this area and your engineer, Westwood Professional Services,
was working on the design of Trott Brook Fanus, we worked together jointly to utilize the wetland
complex as a detention basis (Westwood's wetland report classified this area as a Type 1,2 and 3
wetland complex). There was already a 42-inch diameter storm sewer out of the wetland complex
controlled by a cap skimmer. Owing the development of this whole area, that cap skimmer was
raised four feet and a 12-inch orifice was provided two feet down from the top. The concept behind
this design was that in a lOO-year rainfall event, storm 'Water from the tributaty area lying north of
CSAH 12 would reach this wetland complex and most of it would be held for a period of time and
then slowly let out through. the 12-inch orifice over a period of 24 - 48 hours after the storm.
Somewhere between the last 12 - 24 months the orifice became plugged. City staff'W3.S aware of this
plugged orifice, but only monitored the situation until recently. With the development of the Trott
Brook Farms 11 ch Addition, it became clear that the high water level in the wetland complex due to
the plugged orifice was problematic. The aty Street Department unplugged the orifice
approximately two weeks ago and the pond drained do'WIl over a period of a couple days. In
reviewing the outlet structUre after the water had been lowered, we discovered that the orifice pipe
had settled at least a foot. We are now working to correct the outlet strncture to re-establish the
nomlal water level, which will be at least one ioot higher and may be slightly .
more than the current wetland complex water elevation. We cornznitted to the City Council to have
this completed within approximately two weeks.
If you have any further questions about this issue or would like to discuss it further, please call me at
763/635-1051.
Sincerely,
c;--.
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Teny J. Maurer, PE
Gty Engineer
Phone: 763.63;.1000
Pax: 763.635.1090
www.cl.elk-river.mn.us
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