B West Water Treatment Plant
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
5
-
MEMORANDUM
TO:
Todd Gerhardt, City Manager
FROM:
Paul Oehme, Dir. of Public Works/City Engineer ~ ~
d~
DATE:
July 11,2005
SUBJ:
West Water Treatment Plant Land Acquisition DiscussionlPark
Concept Project No. 05-06
This memorandum is intended to summarize the decisions made by the City since the
2003 Water Master Plan was completed and identify cost benefit analysis for land
acquisition for a future west water treatment plant.
BACKGROUND
In January, 2003, a Master Plan was completed for the City of Chanhassen. This plan
included recommendations for water supply, treatment and distribution the system.
Some of the recommendations in the plan were of concern to the City Council and the
Citizens Advisory Panel (CAP) and a review by a separate consultant of the plan was
recommended. The concerns included phasing in of the water improvements, cost
analysis, and recommendations for a central plant.
On August 20,2003, SEH Consultants completed a review of the 2003 Water Master
Plan and recommended a stepwise approach to address the City's water quality
issues. This approach proposed to address the most urgent needs for the City and
then move on to address less urgent water quality needs.
The approach laid out by SEH was as follows:
A. On the east well field:
1. Meet the Minnesota Department of Health Requirements.
2. Meet the Safe Drinking Water Act requirements.
3. Reduce colored water and taste/odor problems.
4. Mitigate bacteriological risks in the distribution system.
5. Expand supply without compromising the first four objectives.
B. On the west well field:
1. Assess the reliability of sequestering.
2. Phase in treatment as needed.
On December 18, 2003, the CAP met and discussed the SEH August 20, 2003
recommendations. The CAP unanimously suggested the Chanhassen City Council
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. wurk. and play
Todd Gerhardt
July 11,2005
Page 2
proceed with steps to investigate and implement a multiple treatment plant approach
to address the City's short- and long-term water supply and treatment needs.
The Chanhassen City Council met on January 5, 2004 in a work session to review the
work of the CAP and discuss the recommendations. The meeting ended with the
Council approving the CAP's recommendation for the multiple treatment plant. On
the January 26,2005 regular agenda, the Council adjusted the connection charges and
water rates to help pay for the future water treatment improvements.
On April 12, 2004, the Council met and reviewed the discussions the CAP and City
Council made from December 2003 to January 2004 and evaluated the water
treatment alternatives. At this meeting, it was determined to build the (East) Lotus
Lake water treatment plant to its ultimate design capacity, 6,000 gpm, instead of the
phased approach as recommended in the August 20, 2003 SEH memorandum. This
discussion was made because it was anticipated the expansion to the plant would be
needed only a few years after the first phase of the plant was built because of
projected City growth. Also, by building the treatment plant to the ultimate capacity
under one construction project, costs would be less and disruption to the
neighborhood by construction traffic would be minimized.
The Council directed staff to obtain quotes for three studies:
1. Groundwater Modeling Study of the Lotus Lake Well Field. This report was
needed to identify if adequate water supply was available in this area to
supply the plant for the ultimate design capacity.
2. Pilot Plant Modeling Study. This report was needed to identify the best way
to treat the water at the Lotus Lake Well Field.
3. Preliminary Investigation Study. This report was needed to define the best
location to build the plant.
At the June 14,2004, Council work session staff presented the findings of the three
reports to the Council. The Council accepted the groundwater modeling and pilot
plant study. The Council requested additional information including some cost and
benefit analysis for the two available sites, the "Ready Mix Site" located just north of
TH 5 by the pedestrian bridge and the South Lotus Lake Park site. The two sites
identified in the report were the only available properties near the east well field the
City owned. Both sites are very tight and have unique challenges for constructing a
water treatment plant.
At the August 9, 2004, work session staff updated the Council on the recommended
location of the Lotus Lake well field site. The Council unanimously approved
moving forward with sighting the water treatment plant on the "Ready Mix Site" by
the TH 5 Pedestrian Bridge. Since the August 9,2004 Council meeting, staff has
been working on the design of the East Water Treatment Plant. The east plant is
scheduled for construction start in July 2005 and to be operational in 2006.
Todd Gerhardt
July 11,2005
Page 3
The August, 2003 SEH memorandum recommended the City assess the possibility of
sequestering the iron and manganese for the west wells. Sequestering was also
reviewed in the 2003 Master Plan. The sequestration process adds polyphosphates to
the effluent water and in turn reduces the formation of insoluble iron and manganese
oxides which cause the water discoloration, staining, and taste and odor problems.
Staff obtained costs for sequestering the west well water. Using average pumping
rates from these wells, chemical injection cost will average about $32,000.00/yr.
Initial startup costs will be approximately $5,000.00 for tanks, pumps and injection
point installation.
The effectiveness of sequestration can be limited by concentration of constituents and
water temperature. In addition, polyphosphates can begin to break down within 24
hours or less, reverting to an orthophosphate which has no sequestering capability.
Also, orthophosphates can serve as a nutrient to water system bacteria and other
microbes. Hence, retention time within the water system is a critical element for
deciding on its use. The recent testing done on the wells and pumping records
concluded that the residence time in the west well field during the fall and winter
months is estimated to be too long for sequestering to be effective. In addition the
west side of the City has numerous long dead ends that are not looped which make
sequestering ineffective at times. The 2003 Master Plan deemed this process not
feasible. The analysis showed sequestration would most likely not be effective
during the fall and winter months when the process is needed the most. Due to the
high annual cost of chemical injections staff is not recommending sequestering be
considered in the west well field. A treatment plant that removes the iron and
manganese is the recommended method for improving the aesthetics of the west well
water.
LAND ACQUISITION FOR WEST TREATMENT PLANT
The 2004 and 2005 Capital Improvement plans adopted by the Council included a
project, #W-031, for land acquisition for the west (Galpin Area) water treatment
plant. Over the past two years, staff has looked for opportunities to purchase land in
the Galpin area for a future water treatment plant. Staff began site evaluations based
on the 2003 Water Master Plan and evaluated other sites in the corridor as they were
put on the market and became available. The City has not considered eminent
domain or land taking at this time for water treatment plant site.
Over the past two years, five sites were evaluated for a water treatment plant in the
Galpin Boulevard area. This area was chosen based on its close proximity to the west
wells were existing infrastructure already is in place. The closer the water treatment
plant is to the existing and future wells, the less raw water transmission mains will be
needed.
Through the Highcrest Meadows and the Lake Harrison development, the City is
considering installing raw water transmission mains to be used for a future treatment
Todd Gerhardt
July 11,2005
Page 4
plant (Section A). The transmission mains are proposed through these developments
because it is the most cost effective alignment to bring the raw water from Well Nos.
7 and 8 to a future treatment plant in the Galpin Boulevard area. Any other alignment
along existing street right-of-way will cause significant disruption to the property
owners and the traveling public and would be more expensive. All sites evaluated
would utilize the transmission mains.
SITE ANALYSIS
Alternative Site 1 - This site is located at the southwest quadrant of the intersection
of Galpin Boulevard and Topaz Drive. The site is approximately 5.4 acres. The
majority of the site is on a steep hill with few mature trees. The site is centrally
located around the western wells and is close to the distribution network. The site is
also centrally located between the high zone and the low zone areas. The treatment
plant would be designed to pump water to the high zone and the low zone without the
need for an additional external booster pump station. The site allows for the
treatment plant to be built into the hillside and partially screened from the existing
and future residential neighborhoods (see attached concept plans). Building the
treatment plant into the hillside will add approximately $100,000 to the construction
of the plant. Properties on the east side of Galpin Boulevard would be screened from
the plant by a berm. In addition, these properties are setback from Galpin Boulevard
by a wetland along the east side of Galpin Boulevard. Additional raw water and
distribution pipe network would be required to bring the raw water from Well Nos. 9
and 3 to the plant and distribute it out into the network at an estimated cost of
$390,000 (Section B). The purchase price for this site is estimated at $1,300,000.
The Parks Department has identified this site as a good location for a small
neighborhood park and sledding hill. Funds for purchasing the property would come
from the water utility fund and park dedication fund. The 2003 Master Water Plan
considered this site desirable for a water treatment plant.
Alternative Site 2 - This site is located at the southeast quadrant of the intersection of
Galpin Boulevard and Longacres Drive. Well No.3 is south of the site and Well No.
9 raw water transmission main is close to the site. The site is also close to the high
and low pressure zones. The treatment plant would be designed to pump water to the
high zone and the low zone without the need for an additional external booster pump
station. A 20" raw water transmission main would be required to be extended along
Galpin Boulevard (Section B) from the Lake Harrison Development to the site in
addition to some distribution mains. The cost for the piping is estimated at $410,000.
Based on the topography of the land and future access of the site for development, it
is estimated 4.5 acres of land would be needed for the plant. The current land value is
estimated at $1,269,000 using $282,000/acre. The plant would be built in a
residential neighborhood and the lay of the land does not allow for much screening.
The treatment plant would be visible to the Longacres neighborhood on the west side
of Galpin Boulevard. The property is currently not for sale. If the City would
condemn the property, costs for land are anticipated to be higher. The 2003 Master
Water Plan rated this site low and did not consider it a desirable site because the
f
l
Todd Gerhardt
July 11,2005
Page 5
shape of the parcel would make it difficult to provide adequate buffer between the
water treatment plant and the adjacent residential parcels.
Alternative Site 3 - This site is located at the northwest quadrant of the intersection of
Galpin Boulevard. and Walnut Curve. This property was for sale in 2004 and staff
evaluated the property at that time for a water treatment plant. The property is
approximately five acres, however, about 25% of the property is considered wetland.
The property is also very narrow. Based on the setback requirements for the
treatment plant from wetlands and adjacent properties, it was determined the property
was not adequate for a treatment plant.
Alternative Site 4 - This site is located at the northwest quadrant of the intersection of
Galpin Boulevard and 78th Street. This property is for sale and staff has reviewed the
site for a water treatment plant. The site is approximately seven acres and is located
near a trunk sanitary sewer that is on the north side of the property. Approximately
50% of the property is wetland. Staff obtained soil borings for this site which show a
significant amount of poor soils at the site at the buildable location. The setback
requirements from the Department of Health for the wetlands and the sanitary sewer
make the site too small for a water treatment plant.
Alternative Site 5 - This site is located at the southwest quadrant of the intersection
of Galpin Boulevard and 78th Street and is approximately 8.08 acres. The south side
if the property abuts TH 5. This property is for sale and is currently zoned residential
low density. The property has a small wetland on the west side of the property.
Access would only be available on the west end of the property off of 78th street.
Based on the available access point and the wetlands, the entire site would need to be
purchased to build a water treatment plant. The property is being marketed at $lO/sf.,
or $3,520,000 for the 8 acres.
The site is in the low pressure zone and a substantial amount of piping improvements
would be required to make the site functional for water treatment. A 20" raw water
transmission main would be needed along Galpin Boulevard from the Lake Harrison
Development to Well No.3 similar to Site 1 and Site 2 needs (Section B). The
existing 16" main between Well Nos. 3 and 9 would need to be removed and replaced
with a new raw water transmission main (Section C). A new 24" raw water
transmission main would be required from Well No.9 to the treatment plant (Section
D). These improvements are necessary to bring the raw water to the treatment plant.
In order to have the plant service the high pressure zone, an external booster pump
would need to be built at Sites 1 or 2 or a 16" dedicated high zone distribution main
would be required along Galpin Boulevard from the treatment plant to Longacres
Boulevard. For this analysis, the 16" distribution pipe was used because it is less
expensive then a booster pump station. The total estimated cost for the raw water
transmission and distribution piping to make this site adequate for water treatment is
$1,071,000.
Todd Gerhardt
July 11,2005
Page 6
The site is away from residential parcels and therefore considered a desirable site.
However, due to the land cost and additional infrastructure to make this site a viable,
the site is not considered desirable.
Summary of Site Issues
Added Screening! Land
SITES Facility Cost Piping Cost Land Costs
for Screening Buffering Availability Total
Site 1 $100,000 Adequate $390,000 $1,300,000 Available $1,790,000
Site 2 ? Nota $410,000 $1,269,000* Not $1,679,000
desirable site available
Site 5 - NA $1,071,000 $3,520,000 Available $4,591,000
* Does not include condemnation costs (attorney, appraisals, etc.)
? This site is visible from all directions and screening will be an issue.
Sites 3 and 4 were not included in the summary because they did not meet the
minimum requirements for the west water treatment plant site.
CONCLUSION
Site 5 costs substantially more then Sites 1 and 2 and is therefore not recommended
for a treatment plant site.
Based on the available information, Sites 1 and 2 cost benefit is very similar when
compared to the estimated $9,000,000 to construct the treatment plant. Since Site 2
land is not available for purchase and is not a desirable site for a treatment plant based
on screening and buffering issues in a residential area, it is recommended the City
consider purchasing Site 1 for the west water treatment plant.
FUNDING
If the Council wishes to pursue land acquisition for the west water treatment plant
site, staff is recommending funding $760,000 of the purchase from the Water Utility
Fund and $540,000 from the Park Dedication Fund.
Attachments
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. --West Water-Treatment PlanT'slte
City of Chanhassen, Minnesota
CONCEPT PLAN
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