City Council Minutes 05-22-1995 SpecialMINUTES
SPECIAL MEETING - MONTICELLO CITY COUNCIL
Monday, May 22, 199b - b p.m.
Members Present: Brad Fyle, Shirley Anderson, Clint Herbst, Brian Stumpf, Tom
Perrault
Members Absent: None
A special meeting of the City Council was held for the purpose of interviewing the
following four engineering consultant firms for the wastewater treatment plant
expansion project.
1. Short Elliott Hendrickson Inc. (,SEH)
SEH was represented by John Stodola, Bob Stark, and Kurt Mayer. John
Stodola noted that SEH is very experienced and would be able to meet
Monticello's required time table for construction. They have an excellent
working relationship with the Minnesota Pollution Control Agency, would
provide continuous open communication during the project, and can help the
City obtain financial assistance.
Bob Stark suggested that the City consider an oxidation ditch process rather
than duplicating the present system as referenced in the facilities plan, as
the oxidation ditch process could reduce construction cost far the immediate
project and long-term future expansions. The oxidation ditch process offers
many advantages over the present treatment system such as: 1) providing a
high level of nitrification, which will meet more stringent effluent
requirements, 2) a longer detention time and can easily handle high loads, 3)
drastically reducing pumping requirements, which reduces operation cost,
and 4) allowing fnr cost-effective, organized plant expansions.
Stark also suggested the following changes to the facilities plan:
1) installation of static fine screens in lieu of a new interim primary clarifier
to remove solids, 2) converting existing intermediate clarifiers to chlorine
contact basins in lieu of construction of an additional chlorine contact basin,
3) converting the existing anaerobic digesters to aerobic digesters, and 4)
converting the two existing final clarifiers and two existing aeration basins
into sludge storage. It was noted by John Stodola that they would amend the
existing facilities plan to include the suggested changes rather than rewrite
the entire plan.
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Public Works Director Jahn Simala asked whether converting the anaerobic
digesters to aerobic would result in more or less odors, and would the final
sludge product be more or less treated. John Stodola stated that aerobic
digesters will not create additional odors, and the suggested treatment would
result in class B sludge.
2. T ltz„~g, Duvall. Anderson & Associates, Inc. (TKDA)
TKDA was represented by Dave Kirkwold, Bob Gallery, and Duane Prew.
Dave Kirkwold stated that it was their view that the current facilities plan
was too costly for a city of Monticello's size and suggested that the City
consider either an oxidation ditch process or a trickling filter/solids contact
process.
Kirkwold explained that an oxidation ditch system would be comprised of two
new primary clarifiers, two oxidation ditches, and two new final clarifiers,
which would be constructed off line and would be hooked up when
construction was complete. This system would reduce the number of pumps
needed to operate the plant. He also noted that it may be possible to use the
current aeration basins and clarifiers as sludge storage tanks.
Bob Gallery explained that another alternative is the trickling filter/solids
contact process, which minimizes the amount of activated sludge process.
There would be no need for additional aeration tanks, and it would have the
ongoing benefit of not having to expend energy to aerate the water.
Gallery also noted that an oversight was made when preparing the proposal,
and engineering costs would need to be added. It was also noted that the
existing facilities plan would be amended by TKDA to incorporate the
necessary changes.
Public Works Director John Simola asked what type of sludge would be
produced with each alternative, and if the process would be anaerobic or
aerobic. Dave Kirkwald stated that the anaerobic digester process would be
utilized, and the sludge would be similar to what is currently produced.
Councilmember Anderson asked if TKDA's proposal included the cost to add
odor control. Kirkwold responded that the cost to construct odor controls
would need to be added to each alternative.
Simola questioned whether either process suggested by TKDA would lead to
easier odor control, especially in light of the egg processing facility located in
town. Kirkwold noted that the possibility for emissions is moat prevalent in
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the primary clarifier and that the trickling filter/oxidation ditch would be
comparable to the current treatment; however, construction of a small
aeration basin for the primary clarifier could be studied to help control odor.
3. HDR Engineering, Inc.
HDR was represented by Bob Peplin, Kurt Sparks, and Scott Wallace. Bob
Peplin noted that HDR has sufficient experience to stay on budget and stay
on schedule for this project. It was also noted that they have an $5% ratio on
return customers, indicating that customers have been happy with the work
completed by HDR in the past.
Peplin suggested that the City consider two additional alternatives to that
suggested in the facilities plan: 1) an oxidation ditch process, or
2) sequencing batch reactors (sbr). These alternatives would result in a
better plant for less money, would require only 6 pumps versus the 60 pumps
needed with the current plant, and would result in the ability to construct
the new addition while continuing to use the current plant. These
alternatives would also simply future expansion and would provide the
ability to use common-wall construction to help minimize the cost of future
development. Peplin noted that the total cost of the project should be
between $5 million and $7 million, including odor controls, which calculates
to $2-$3 per gallon versus the present $6.50 per gallon at the current facility.
Peplin went on to explain that the system suggested by HDR would upgrade
the sludge from class B to class A, which is pathogen free and would
eliminate the City having to search for land application sites. The class A
sludge can be disposed of as a fertilizer in ways such as selling to a farm coop
ar bagging it and distributing to city residents.
Scott Wallace proposed that the City use the sequencing batch reactor (sbr)
process, which could be sized for 4 mgd and beyond. He explained that a new
lift station would be constructed at the head of the plant, and the wastewater
would then enter the sbr process. The wastewater enters the tanks, is
aerated, then aeration is turned off and the tanks settle, which acts as a
clarifier. The flow is cycled between the tanks. This process combines much
of the current process into four tanks. The wastewater then goes through the
final disinfection process and is discharged to the river. As the city grows,
only an additional treatment basin is added. Wallace also noted that the
existing tankage could be reused to avoid the cost of additional tank
construction.
Kurt Sparks reported that the proposed treatment facility will meet new and
future permit regulations and that nitrogen and phosphorus removal
facilities can be added as required.
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Bob Peplin noted that the oxidation ditch system is a goad process that could
also be used; however, the disadvantage is that it requires a large amount of
concrete and could be up to two times the size of the sbr process.
John Simola asked what treatment is proposed to achieve the proposed
class A sludge. It was noted by HDR that some plants use aerobic treatment
and others use lime to achieve the class A sludge.
Simola also asked whether the sbr units could adapt to increased nutrient
limits. Scott Wallace replied that the sbr process is good for nutrient removal
because the aeration equipment can be sized to oxidize the ammonia to
nitrate.
4. RCM/OSM
RCM/OSM was represented by Sam Claassen, Ed DeLaForest, Larry
Anderson, and Charlie Weerts.
Sam Claassen noted that the RCM/OSM team prepared the facilities plan far
the City of Monticello and that there may be some minor updates to make to
the plan. He encouraged the City to consider joint solids handling with the
City of Buffalo as a solution to the City's difficulty in finding land for sludge
application. Buffalo is considering lime stabilization and compacting with
Wright County. Claassen also noted that, although the facilities plan is
based on achieving class B sludge, it maybe in the best interest of the City to
consider class A sludge, and RCM/OSM would be willing to explore other
alternatives to those suggested in the facilities plan. Claassen also suggested
that the City undertake an odor control study and that constructing the
project in phases would be the mast cost-effective way to expand the
treatment plant.
Kelsie McGuire of PSG commented that other firms have presented
alternatives to the facilities plan and asked if RCM/OSM had considered the
sbr process or an oxidation ditch process. Larry Anderson responded by
stating that they were not convinced that the sbr process would meet the
10 mgl BOD standard with high strength waste entering the plant. He also
noted that it was their view an oxidation ditch system would not be cost-
effective for the Monticello plant due to the site being located on a hillside.
At the conclusion of the presentations by the four engineering firms, the meeting
was ad' urned.
;,
n Doty
Office Manager
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