1e. Lift Station No. 3 Improvements, Project 07-03: Approve Consultant Contract
CITY OF
CHANHASSEN
7700 Market Boulevard
PO Box 147
Chanhassen, MN 55317
Administration
Phone: 952.227.1100
Fax: 952.227.1110
Building Inspections
Phone: 952.227.1180
Fax: 952.227.1190
Engineering
Phone: 952.227.1160
Fax: 952.227.1170
Finance
Phone: 952.227.1140
Fax: 952.227.1110
Park & Recreation
Phone: 952.227.1120
Fax: 952.227.1110
Recreation Center
2310 Coulter Boulevard
Phone: 952.227.1400
Fax: 952.227.1404
Planning &
Natural Resources
Phone: 952.227.1130
Fax: 952.227.1110
Public Works
1591 Park Road
Phone: 952.227.1300
Fax: 952.227.1310
Senior Center
Phone: 952.227.1125
Fax: 952.227.1110
Web Site
www.ci.chanhassen.mn.us
ie...
MEMORANDUM
TO:
Todd Gerhardt, City Manager
Paul Oehme, P.E., Dir. of Public Works/City Engineer"'Y..dJ..
FROM:
DATE:
February 12, 2007
fJ~'
SUBJ:
Lift Station No.3 Improvements, Project No. 07-03: Approve
Consultant Contract
REQUESTED ACTION
Approve consultant contract with WSB & Associates
Improvements.
Lift Station No.3
BACKGROUND
Lift Station No.3 is located on the north side of
Church Road. The station is the main collection
western portion of the city and picks up flows
The flows from Lift Station No.3 go directly i .
system. The service area of Lift Station No.3 has seen sever
developments approved recently.
7 just west of
in the
tations.
cil sewer
The station was identified as a problem after revie\Vingitl1e
after the new SCADA systemwas install<ed.Ar~~ie
hourly cycles for this station revealed thepumpsar
which is indicative of insufficient wet wellcapasitYt
pumps. There is less than one.(l) foot.ofwrtw<ell()~
pumps start and shut off. This means the P\lJ.rlpshav~
working range which limits the amount of timethepu
and increases the number of times that thepumpsstartanqst()
pumps are constructed in such a manner that longerrunti~es
stops and starts per hour (cycles) providedfor.along<erservic<e. > r the pumps.
High rate cyckson an hourly basis result in increased\V~arftI1g~tress on the
pumps and increased levels of pump maintenan()eand~~placem<e~t'.'The
increased cycles of the pumps can be attributedtqadcl.itional flow~~9
developments in the area. The increased cycling will only increase as
developments are built out.
The upstream service area for this lift stationwasidentified as a priority area in
the "Sanitary Sewer Infiltratic5nlanQ!:~:urJ}0-w.Reducti0n Plan" for inflow and
infiltration (III) removal. As a result of the III analysis, staff is concerned with the
The City of Chanhassen . A growing community with clean lakes, quality schools, a charming downtown, thriving businesses, winding trails, and beautiful parks. A great place to live, work, and piay.
Todd Gerhardt
Lift Station No.3 Improvements
February 12, 2007
Page 2
operation of Lift Station No.3 and its ability to accommodate additional
wastewater flow from a new development west of the lift station site.
The operational problems discussed previously are a cause for concern due to the
construction of new single-family homes constructed within 300 feet of the lift
station. The new development is west of the lift station and is connected to the
lateral sewer discussed in the previous paragraph. Staff is concerned about
backups into the new development area if pumps fail or power is interrupted.
PROJECT APPROACH
Staff has envisioned reconstruction of the lift station to minimize the City's
potential liability. The following conditions are proposed to be addressed at the
lift station:
.
Currently, the elevation of the sanitary sewer lateral extending westerly is
serving the new development and is very close to the high water alarm
elevation in the lift station. If the station goes down for any reason, there is
very little time before the lift station wet well fills up and backs up into the
line going to the new development. A new wet well is proposed to provide'
adequate storage for ultimate flows. It is anticipated the old wet well will be
abandoned.
.
The power supply to this site is overhead and highly susceptible to power
outages. Due to the amount of flow to the station and the distance the lift
station is from the utility operation center, a secondary power supply (standby
generator) is recommended. A permanent on-site generator should be
installed at the site to minimize the potential for power interruption. The City
has backup generators at other high volume lift station sites such as Lift
Station No. 10 by Lotus Lake. A new control panel to run the station is also
required.
.
From Engineering Dept. records, Lift Station No.3 was installed in June,
1972. The pumps in this station were replaced in 2000. An analysis of the
service area and design flows for the replacement pumps was not completed at
the time. In conjunction with this project, an analysis shall be completed to
determine if the pumps are sized properly for the existing and future design
flows and new head (pumping) conditions of the wet well. A service area
analysis should be completed to determine ultimate waste water flows coming
to the station.
.
Poor soils are expected at the new wet well site. Open cutting for construction
of the new wet well may not be an option due to right-of-way constraints. A
cost analysis should be completed to determine the best available construction
technique for the wet well installation.
Todd Gerhardt
Lift Station No.3 Improvements
February 12,2007
Page 3
PROPOSAL
Staff received two proposals for this project as follows:
Firm
Proposal
$43,295.00
$49,740.00
WSB & Associates
Kimberl y Horn & Associates
WSB & Associates currently is working on the III reduction project for the City
and the Sanitary Sewer Comprehensive Plan update. Their work has been
acceptable.
The project was budgeted for in the 2007 CIP (SS-017) and would be funded
through the sanitary sewer utility fund.
RECOMMENDA TION
Approve Consultant Contract with WSB & Associates for Lift Station No.3
improvements in the amount of $43,295.00.
Attachments
c: Kelley Janes, Utility Superintendent
Todd Hubmer, WSB & Associates
g:\eng\public\07-03 lift station no. 3\021207 bkgd apprv consultant contract.doc
Capital Improvement Program
City of Chanhassen, MN
2007 thru 2011
Project #
SS-017
Project Name Sanitary Lift Station Rehabilitation Program
Account#l 701-0000-4751
Account # 3
Account #2
Contact Unassigned
Department Sanitary Sewer hnprovements
Type hnprovement
Usefut Life Unassigned
Category Utilities
Priority nfa
"...'1'btlll Project Cost $475,000
Description
The sanitary lift station rehabilitation program is designed to minimize sewer backups and emergency calls due to failed lift station equipment. The
City currently maintains 30 lift stations. Many of these lift stations are high service pumps and need frequent servicing. The program will service
or replace pumps, pipe gallery, and electrical components as needed. Lift Station #3 is recommended for improvements in 2007. Lift Station #3
located on the north side of Highway 7 takes all the flow from the properties on the west side of Lake Minnewashta and properties on the north side
of Highway 7. The wet well capacity has become undersized for flows. The electrical panel hlis become unreliable and needs to be replaced. The
electrical power in this area is unreliable, so a permanent backup generator is recommended.
Justification
Reduce emergency calls and potential sewer backups.
2007
265,000
Total 265,000
2008
50,000
50;000
2009
50,000
50,000
Expenditures
Maintenance
Funding Sources
Sewer Utility Fund
2007
265,000
Total 265,000
2008
50,000
50,000
2009
50,000
50,000
89
2010
55,000
55,000
2010
55,000
55,000
2011
55,000
55,000
2011
55,000
55,000
Total
475,000
475,000
Total
475,000
475,000
Lift Station 3 Service Area
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January 30, 2007