1f. Well No. 14: Approve Plans and Specs and Auth Ad for Bids
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
14;
MEMORANDUM
TO:
Todd Gerhardt, City Manager
o
Paul Oehme, Director of Public Works/City Engineer (ll
FROM:
DATE:
December 14, 2009
,~
SUBJ:
Well No. 14 Project 10-03: Approve Plans and Specifications and
Authorize Advertisement for Bids
PROPOSED MOTION
"The City Council approves approve the plans and specifications and
authorizes advertisement for bids for Well No. 14."
City Council approval requires a simple majority vote of the City Council
present.
BACKGROUND
At the January 12,2009 Work Session, staff discussed the Well No. 14 improvements
along with the Well No.4 water quality improvements.
On November 9, 2009, the Council approved a consultant contract for design of Well
No. 14.
DISCUSSION
Well No. 14 is recommended to be constructed to keep face with peak summer water
demand of the community. Well No. 14 will be the 11 t well for the City and is
proposed to be a Jordan aquifer production welL The water for this well will be
treated at the East Water Treatment Plant. The well would be located on north side of
Lake Drive across from Lake Susan Park. The well would use the proposed raw
watermain that Well No.4 would use to convey the water to the plant for treatment.
Staff is proposing this well for several reasons:
1. To address the failure of Well No. 11 to yield adequate water supply to the
plant. Well No. 11 is in the same drift aquifer as the failed 2007 Well Nos. 5
and 6. Since those failures, Well No. 11 has not preformed consistently as a
production well. The well currently has only 20 feet of static water level
cover which is not adequate to keep air from vortexing into the pump causing
a damaging condition known as cavitation. It is not practical to lower the
pump-set in this compromised aquifer.
Chanhassen is a Community for Life. Providing for Today and Planning for Tomorrow
Paul Oehme
Well No. 14: Approve Plans & Spec.; Authorize Ad for Bids
December 14,2009
Page 2
2. If approved, the addition of Well No. 14 should add approximately 1000 GPM
of treated water into the City's distribution system. During the peak summer
months, untreated water must be used to augment the treatment plant's
production of finished water. The addition of Well No. 14 will allow staff to
maximize our treatment plant investment, increasing treated water capacity
from 6,100 GPM to 7,100 GPM (6,100 GPM includes Well No.4 production).
3. The Jordan aquifer on which much of the Twin Cities metro relies on is
experiencing a downward trend in static levels. Chanhassen's Well No.2 has
seen a 30-foot drop in pumping level since 1984. The new Well No. 13 had a
10-foot seasonal drop this summer. Well No.3 on the west side of the city
has seen a similar static level drop. Lower static levels means less water
available to pump. With seasonal well capacity diminishing more wells are
needed to keep pace with demand.
4. Even with great efforts by staff over the last two years to educate the
community on water conservation, 2009 will be another record breaking year
for water use. In the first 10 months of2009, Chanhassen has pumped 1.202
billion gallons, more than all 12 months of2008 (1.176 billion gallons). It is
City staff s opinion that our production should continue to keep pace with city
demand with a small allowance for mechanical failure and routine
maintenance.
5. The City continues to grow and add additional irrigation demand. The
addition of the Chanhassen High School, additional residential/commercial
developments and existing residents adding irrigation systems is expected to
add to the summer peak demand. This demand will be exacerbated if we
continue to see below average summer rainfall totals.
DESIGN CONSIDERATIONS
Two methods of construction are commonly used to construct large diameter
municipal wells such as Well 14. They are the dual rotary method, which was used
for Wells 12 and 13, and the cable tool method. Based on experience with Wells 12
and 13 and other wells, the dual rotary method will reliably be able to meet that
schedule. However, Traut Wells is the only driller in the state that regularly bids on
municipal well projects to be constructed with the dual rotary method. If only this
method is specified, there will likely be only one bid.
The cable tool method is used by several other well drillers in this area that regularly
bid on municipal well projects. This method typically takes significantly longer; up
to two to three times as long as a dual rotary drilled well and is not as dependable. A
cable tool driller could meet the schedule for Well No. 14 if they were allowed to
work double shifts (7:00 a.m. to midnight) six days a week. One driller was
contacted and confirmed that they are willing and able to meet such a schedule with
double shifts. There is, however, more potential for delays to extend that schedule
g:\eng\public\_2010 projects\10-03 well no. 14\121409 approve ps add bid. doc
Paul Oehme
Well No. 14: Approve Plans & Spec.; Authorize Ad for Bids
December 14,2009
Page 3
with this method due to mechanical breakdown or unknown conditions in the aquifer.
If this method is allowed, staff would recommend prequalifying drillers by asking
them to show evidence that they have installed at least three wells of similar depth
and design in five months or less.
From a cost standpoint, cable tool wells are competitive with dual rotary wells. If the
cable tool drillers are prequalified then allowing both to bid should result in multiple
competitive bids from drillers that can meet the schedule proposed.
Since Well No. 14 is not in a residential area, staff recommends opening the bids up
to prequalified cable tool contractors.
Staff has sent the Church, whose driveway would be impacted by the construction,
the plan for the project. To date, the Church has not responded back with any
comments about the proposed project. The well is to be built on City-owned
property, however, the Church maintains the property since it is the entrance to their
property.
SCHEDULE
Staff anticipates the following project schedule:
Bid Opening
A ward Construction Contract
Substantial Completion
January, 142010
January 25,2010
July, 2010
Attachments Location Maps
CIP
c: Brian LeMon, Barr Engineering
Kevin Crooks, Utility Superintendent
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Capital Improvement Program 2009 thru 2013 Contact Paul Oehme
City of Chanhassen, MN Department Water System Improvements I
W-043 Type Improvement
Project #
Useful Life I
Project Name Well #14 Improvements Category Utilities
Account # 1 Account # 3 Priority nla
Account #2 Total Project Cost $750,000 I
"
Description I
This well is proposed to meet the water needs of the growing community. I
I
Justification I
~
To meet tbe growing water needs of the City. I
I
Expenditures 2009 2010 2011 2012 2013 Total I
COnstruction 750,000 750,000
Total 750,000 750,000
I
I
Fundbig Sources 2009 2010 2011 2012 2013 Total
Water UtilitY Fund 750,000 . 750,000 I
Total 750,000 750,000
I
.., I
Operational Impact/Other I ",
I
,
I
I
I
138 I