HomeMy WebLinkAbout7.d. Horseshoe Lake Lift Station4ROSEMOUNTEXECUTIVE SUMMARY
UTILITY COMMISSION
Utility Commission Meeting: April 20, 2015
AGENDA ITEM: Horseshoe Lake Lift Station
AGENDA SECTION:
New Business
PREPARED BY: Phil Olson, PE, Assistant City Engineer
AGENDA NO. 7.d.
ATTACHMENTS: Bella Vista Storm Sewer Figure
APPROVED BY:
RECOMMENDED ACTION: Motion to recommend approval of the design and construction
of the Horseshoe Lake storm sewer lift station.
ISSUE
Horseshoe Lake is a landlocked lake located east of Bacardi Avenue and north of Bonaire Path. To
facilitate development in the area, the City reviewed the Stormwater Management Plan and determined
that a storm sewer lift station is reasonable to add at the south end of Horseshoe Lake. The lift station is
proposed to pump storm water south to Mare Pond where it will connect to the City's trunk storm sewer
system. The lift station will also provide flood protection to the White Lake area in the future when storm
sewer connections are made between White Lake and Horseshoe Lake.
The Bella Vista development has incorporated the lift station into their stormwater management plan and
site design. As currently planned, a storm sewer lift station is required to provide flood protection to the
land area adjacent to Horseshoe Lake. It will also allow the Bella Vista development to meet the City's
infiltration requirements by pumping to an onsite infiltration basin during non-critical storm events.
BACKGROUND
Horseshoe Lake is located within the White Lake District subwatershed and it is listed as Department of
Natural Resources (DNR) public water. The lake has a normal water level (NWL) elevation of 934.0 feet
and an ordinary high water (OW elevation of 935.1 feet. An existing home is located on the northwest
shore of Horseshoe Lake and has a low floor opening (LFO) elevation of 938.9 feet.
The Horseshoe Lake lift station design capacity is proposed to provide flood protection and accommodate
ultimate future development as it occurs within the sub -watershed. It will also serve to convey surface
runoff from the proposed Bella Vista development to an infiltration basin adjacent to Autumn Path.
The Bella Vista feasibility report recommends that the infiltration basin be constructed Phase 2 of the
overall development. The current proposed final plat area (Bella Vista 3rd Addition) is only a portion of
Phase 2 and does not include the construction of the infiltration basin. The infiltration basin and
forcemain outlet to the infiltration basin is planned to be constructed in 2016 with the second half of
Phase 2.
The lift station is proposed to be located within the future Bella Vista park. It is proposed to be initially
constructed with a two cubic feet per second (cfs) pump, but will be sized to accommodate a six cfs pump
for the ultimate development scenario. These pumps will begin pumping at an elevation of 934.1 feet
gAutility commission\uc information\20150420 uc horseshoe lake lift station.docx
which will maintain free board requirements for the adjacent homes and follow current DNR regulations.
The six cfs pump will be necessary when the drainage from White Lake is connected to Horseshoe Lake.
A 16 -inch force main is needed to direct storm water to Mare Pond and a 10 -inch force main is needed to
direct stormwater to the Bella Vista infiltration basin. A valve system with sensors and an automatic valve
will regulate the flow direction in the force main. Stormwater will be directed to the infiltration basin
during normal rainfall events and to Mare Pond during critical flood events. A portion of the 16 -inch
force main was installed with Bella Vista 2nd Addition and more installation is planned with Bella Vista 3rd
Addition.
A permit for the lift station was approved by the DNR on January 10, 2015. The permit allows the lift
station to be activated at 933.6 and pump up to 8.5 million gallons annually.
Construction is planned after the roadway and utilities are installed in Bella Vista 3rd Addition. This is
anticipated to be sometime in August or September. The lift station startup is dependent on the
availability of power to the site but is likely in the late fall 2015 or spring 2016.
The lift station, remaining forcemain, and valve system is estimated to cost approximately $760,000.
SUMMARY
Staff is requesting the Utility Commission make a recommendation for City Council approval of the design
and construction of the Horseshoe Lake storm sewer lift station.
E
KROSEMOUNT
MINNESOTA
Main-
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Bonaire Path W A 741
Bella Vista
Figure 3 - Storm Sewer Plan
City of Rosemount MN
N 1
WSB
1 inch = 400 feet ,