1g Test Well 10 Change Order
CITY OF
CHANHASSEN
7700 Market Boulevard
PO Box 147
Chanhassen, MN 55317
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Phone 952.2271100
Fax 952.227.1110
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1591 Park Road
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Web Site
wwwci.chanhassen.mn.us
í
15
MEMORANDUM
TO:
Todd Gerhardt, City Manager
Paul Oehme, Dir. of Public Works/City Engineer \: '>, C
FROM:
DATE:
March 8, 2005
t~
SUBJ:
Authorize Change Order for New Test Well No. 10
Project 04-08A
REQUESTED ACTION
Authorize Change Order for New Test Well No. 10.
BACKGROUND
On May 24, 2004, Council reviewed a Lotus Lake Well Siting Study. This
computer modeling study confirmed the glacial drift and Prairie du Chien-Jordan
aquifers could each provide one new 1,000 gpm (max. rate) well at both the Water
Treatment Plant (WTP) Ready Mix Site and the South Lotus Lake Park Site.
Staff recommended "A test well should be constructed and insta1led at proposed
well sites in the 'Ready Mix' site and South Lotus Lake Park to verify and confirm
the presence, capacities, and water quality of the buried glacial drift aquifer and
the Prairie du Chien-Jordan bedrock aquifer."
. On October 25, 2004, Council authorized a contract with SEH, Inc. to begin
design on the East Water Treatment Plant located at the east end of 79th Street.
As part of the contract, preparation of specifications and solicitation of quotes for
drilling a test we1l and chemical analysis of the water was included. This
information is necessary to proceed with final design of the water treatment plant
to determine if a well is feasible at the site, the ultimate location of the well, the
location of the future roadway, and location of the raw water pipes to service the
well.
On January 10,2005, Council awarded a contract to Traut Wells Drilling for the
future Well No. 10 on the future water treatment plant site.
DISCUSSION
Traut Wells moved on-site with a mud rotary rig on January 19, 2005. The rig
drilled to the level of a typical depth of the drift formation but did not encounter
the geologic formation for a production well. The drift formation is typically a
gravel geologic layer that once was the foundation of a river bed. For a drift well
to have enough capacity for a production well, a minimum of 20' of a gravel layer
The City of Chanhassen · A growing community with clean lakes, quality schools, a charming downtown, thriving businesses, windmg trails. and beautiful parks A great place to live, work, and play.
Todd Gerhardt
March 8, 2005
Page 2
is typically needed. The test well only found 4' of the gravel geologic layer. The
pump test and water sample chemical analysis were not done. The only
remaining work at this location will be for Traut to properly abandon the well.
Staff feels the City should look for another site for a drift well to meet the needs
òf current and future water demands. We have looked at other possible well sites
near the WTP and have consulted with the Minnesota Department of Health
(MDH) on this issue. Last week, the MDH was on site to review the potential
well sites. The next best location is bounded by 78th Street, Hwy. 101, the Twin
Cities and Western RR, and the large Xcel Energy transformer panels (see
attached drawing). This is just across the RR tracks from Lot 2 of the water
treatment plant site. This site should meet the MDH isolation distances for a
municipal well and is close to the new raw water pipeline feeding the WTP. The
only possible isolation distance issue may be the High Water Level from the
nearby stormwater outlet. We don't anticipate this to be a problem but we will
further investigate and confirm. Thus, this site is our recommendation for the
next test well.
Traut's Wells quote to provide a test well at the new location, per the original
specification, is $30,440.00 with chemical analysis. This is the same quote as the
first test well, however, in order to access and drill this site, a different drill rig is
required at an additional cost of $810.00
(For reference, the Keys Well Drilling bid was $31,255.00.)
At this time, staff recommends authorizing a Change Order for New Test Well
No. 10.
Attachment
Cì:\ENG\PUBLlC\04-08A WELL IO\bkgd 030805 bkgrd new test well aut!u.1m:
Proposed Test Well Site
March, £005 A
Go' \ENG \Joleen \EngPr<!jects \Joleen \Paul\ Watertreatment \ Wellsites.mxd