INFORMATION #2 10-04-2010INFORMATION
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MEMORANDUM
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TO: Mayor and City Council
FROM: Justin Femrite, P.E., City Engineer
DATE: October 4, 2010
SUBJECT: 182"a Avenue Storm Sewer and Pond Level
The storm sewer repairs have been completed at the intersection of 182na Avenue and 181St
Lane. The repairs that were completed addressed the pipe heaving problem that developed
across the street in the intersection. The work completed allowed for the removal of the
pipe crossings and separation of the storm water systems on both sides of the street. The
storm water draining from the north side of the intersection drains into the pond on the
north and the water draining to the south side of the intersection drains to a pond further
south. The project alone did not address the water level in the pond area north of 182na
Avenue, which is still a concern as the water elevation is backing up into the storm sewer
system on the north side of 182na Avenue.
The water level of the pond, as shown in the attached figure, was originally designed and
maintained at 895.10. This elevation was raised in 2005 as a reaction to the public support
for maintaining a higher than designed water level in the pond. In 2005 the ponds outlet
control structure was modified to raise the water level in the pond 2-feet to an elevation of
897.10. This higher water level is directly responsible for the heaving problems encountered
in the intersection of 182na Avenue and 181St Lane. Currently the water elevation in the
pond on the north side of the roadway is being maintained at 897.10. This water level is
causing the remaining storm sewer system on the north side of 181St Avenue to sit full of
water. The catch basin on the north side of 181St Avenue has 2.50 feet of water standing in
it. If left uncorrected, the water in the catch basin may freeze solid this winter and prevent
the north half of this intersection from draining.
Phil Hals and I have reviewed the area and agree the water level in the pond north of 182"a
Avenue must be drawn down to the designed elevation of 895.10 for the winter months to
prevent the storm sewer system from freezing and causing additional damage. We are
prepared to make modifications to the outlet control structure which will allow the pond be
drawn down every fall to the originally designed elevation of 895.10. This will allow the
storm sewer system at 182"a Avenue to function as designed through the winter months.
While we would prefer to make this a permanent improvement, in order to maintain this
lower elevation, we understand the public's concern for wanting to see water in the pond.
As such we are proposing to make modifications to the outlet control structure that allows
C:\Documents and Settings\XPMUser\Local Settings\Temporary Internet Files\OLK66\182nd Avenue Storm Sewer and Pond
Level.doc
for the lowering of the water level between November and April then allowing the water to
recharge to the higher elevations through the spring and summer months. This will be
accomplished by placing a valve on the pipe we are proposing to install on the outlet control
structure. This valve will be closed at the beginning of April of every year to allow the level
in the pond to recharge to the 897.10 elevation. The yearly pond recharge will be dependent
on rainfall received in the spring and summer months. If rainfall amounts during the spring
and summer are small, the water level in the basin may not reach the 897.10 elevation.
The City street crews will be completing the modification to the outlet control structure with
materials already on hand. Please call with any questions you have on the corrections
addressed above.
Enclosure
C:\Documents and Settings\XPMUser\Local Settings\Temporary Internet Files\OLK66\182nd Avenue Storm Sewer and Pond
Level.doc