1b Lift Station 10 Improvements CITYOF
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PO Box 147
Chanhassen. MN 553t 7
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MEMORANDUM
TO:
Todd Gerhardt, City Manager
FROM:
DATE:
SUBJ:
Teresa J. Burgess, Public Works Director/City Engineer
June 18, 2002
Receive Feasibility Report & Call a Public Hearing for Lift Station
10 System Utility Improvements- Project No. 01-11 ~
REQUESTED ACTION
Receive the Feasibility Report and Call a Public Hearing for improvements to Lift
Stations 10 and 2 for July 8th.
DISCUSSION
The City has received the feasibility report that considered improvements to Lift
Stations 1, 2, and 10. The report recommends improvements to all three stations.
A copy of the Summary and Recommendations is attached. The entire study is
available on file in the Engineering Department.
This project is proposed to be financed out of the City's Utility Fund. For that
reason, Staff is recommending that the No. 1 and 2 priorities be done in 2002 with
the remaining projects to be scheduled in the Capitol Improvements Plan (CIP)
for future construction.
Attachment: l. Summary and Recommendations Section of Feasibility Report.
c: David and Rachel Igel
g :\eng\public\O 1 - 11Xstaff report 6-24-02.doc
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VII. Summary and Recommendations
The following list of recommendations summarizes a priority list of projects based on immediate
needs identified by this study,
Priority No. Description
Construct the emergency generator portion of Option A at Lift Station No. 10. If
a. privacy fence is desired, it could be built with the generator project or a local
independent contractor could be hired to build a fence, which blends with the
development project. Cost savings and uniformity of appearance may be
achieved throughout the development if other decorative landscaping work is
required in the development. The cost estimate includes the privacy fence and the
generator installation. The remaining dements of the recommended Option A are
included under the 4th priority recommendation.
Estimated Cost: 7,68,700 (with fence)
Estimated Cost: 548,700 (without fence)
Construct Lift Station No. 2 modifications and the new independent forcemain for
Lift Station No. 2. Because of the overloading problem currently being
experienced at Lift Station No. 2, this station needs to be upgraded prior to
rerouting the flow from Lift Station No. 1 into the gravity system contributory to
Lift Station No. 2. This recommended project needs to be coordinated with the
results of the ongoing I/I investigation pertaining to Lift Station No. 2. The
results of that investigation will be used to finalize the lift station and forcemain
size. At this time, it is assumed that the results of the I/I analysis will show that a
Lift Station No. 2 capacity of 450 ~m will be sufficient to handle the required
inflow. This assumptions results in a recommendation to install two new 15 HP
submersible pumps into the existing 6 foot diameter wet well and to furnish and
install the associated new control panel. This assumption also results in a
recommended 8" diameter forcemain. This is the maximum station capacity that
can be accommodated with the existing wet well. If a larger capacity is needed,
then a new wet well will need to be constructed: which would cause a substantial
increase to the estimated cost for this project. At this time, it is also assumed that
the new forcemain will be installed by utilizing directional drilling as needed to
minimize reconstruction costs of the streets and other restoration work. Lastly, the
up~ade in pump size will require the electric service to the site to be upgraded to
a true 3-phase service.
Estimated Cost: $258,000
Construct a parallel 10" forcemain adjacent to the 6" forcemain from Lift Station
No. 1 to the existing 8" forcemain on Frontier Trail. Flow from Lift Station No. 1
Lift Station No. 10 System Utilit7' Improvements
FeasibiIiu Report
Page 25
will pump to the gravity sewer on Frontier Trail utilizing the existing 6"
forcemain. The gravity flow from this point flows to Lift Station No. 2. Near
Lift Station No. 1, the existing 8" forcemain from Lift Station No. 10 would be
connected to the new section of 10" forcemain, and it would be disconnected
from the existing 6" forcemain. Again, it is assumed that directional drilling
could be utilized to minimize disruption to the adjacent properties. It is also
recommended that the existing pumps in Lift Station No.1 be downsized to reflect
the much lower TDH that will be seen at this lift station. This will provide the
City with an ongoing energy savings.
Estimated Cost: $131,000
Construct the remaining options listed in Option A as an equipment upgTade and
control panel replacement project. The addition of a 10 foot diameter wet well
will improve cycle times and increase the response time available to the City in
an emergency. The existing control panel should be upgraded by the addition of
level sensing equipment for the new wet well, additional surge protection,
additional telemetry points, and spare parts including starter, phase monitor,
relays, timers, overload relays, circuit breakers, and fuses. In order to improve
the aesthetics at the site, it is recommended that a new lighting pole be installed.
It is recommended that the three existing gate valves be replaced, and that the
new wet well be piped into the forcemain so that the City could drop the existing
spare into the new wet well in the event of an emergency. A mobile starter panel
that would plug into the emergency generator and into the pump cable would also
be provided to facilitate running the temporary pump. Odor control, in the form
of activated carbon style forced air filters could be added to the wet well vent pipe
system if odors become a nuisance. Since the flow throuzh this lift station is
primarily fresh domestic waste, odor control equipment m;y not be necessary.
Estimated Cost: $141,300 (with odor control)
Estimated Cost: $ 91,300 (without odor control)
Due to the high cost of Option B and C and the lack of additional benefit to the City, Options B
and C are not recommended improvements.
Lift Station No. 10 System UtiliO, h~zprovements
FeasibiliO, Report
Page 26