Loading...
HomeMy WebLinkAbout1998-11-18 PACKET 13.C.REQUEST OF CITY COUNCI� ACTIC7N COUNCIL AGE�IDA MEETING ITEM # DATE 11/18/98 . PREPARED BY Ice Arena Dean Mulso ORIGINATING DEPARTMENT STAFF AUTHOR � a x w ,t � � < w a r � a < + + > x � �r � + � + > + a � x � s +: e a + « � + s � x + + :t x < * a COUNCII ACTION REQUEST: Workshop—Ice Arena Repairs to the Studio Rink BUDGET IMPLICATION SUPPORTING DOCUMENTS: BUDGETED AMOUNT ACTUAL AMOUNT � MEMO/LETTER: Memo from Dean Mulso ❑ RESOLUTION: ❑ ORDINANCE: ❑ ENGINEERING RECOMMENDATION: ❑ LEGAL RECOMMENDATION: ❑ OTHER: ADMINISTRATORS COMMENTS: � �P City Administrator t f l � G'�' Date t + � � < a �e t a � c + e e � n < t z :t t + x n < e e * t � + � t � i t � � a + a x e < � + � � COUNCIL ACTION TAKEN: ❑ APPROVED � DENIED ❑ OTHER pocument3 TO: Honorable Mayor and City Council FROM: Dean Mulso SUBJECT: Ice Arena Repairs to the Studio Rink DATE: November 18, 1998 - Workshop ISSUE On June 11 1998, The City of Cottage Crrove opened sealed bids for the repair of the Studio Rink at the Ice Arena. The bids received were higher than originally anticipated. Because of this the Council did not accept the cunent bids. However, in separate action by the Council, ALTERNATE #1 (New Compressor Motor} and ALTERNATE #2 (Freon Leak Detection, E�aust Fan) staff was authorized to quotes and proceed with the completion of these two projects. The cost of these to projects came in at $17,507.00. The direction at that time was to re-bid the remainder of the project in eazly 1499. City Staff has put together a proposal to be considered for the re- bidding ofthis project. PROJECT DESCRIPTION 1) Reniacement Of Studio Rink Floor — Partial dernolition of existing floor and the construction of a new sand surface, direct refrigerated rink floor at the same location as previously based bid. 2) Install Freon Float Controls — Replace existing timers with new freon float controls (original bid ALTERNATE 3— not awarded). New Freon Float Controls — We aze proposing new Freon Float Controls to replace our current timers. Currently, we are replacing the timers approximately every 45 to 60 days because of timer failure. Each tune we must send the timers in to be rebuilt because they are not manufactured any longer. Float controLs run on the pressure of the freon flowing through the refrigeration system. Timers have an electrical motor and electrical components, where as the float controls have very few internal parts. For that reason alone, little repair is needed for float controls as opposed to the timers. 3) I'rovide Needed Imnrovements To Refrigeration System (original bid ALTERNATE #4 not awazded) a) Replacement of Two-Bucket Traps - They aze used to collect the debris that may get into the refrigeration system. The traps are original and are showing their age. These traps can be replaced while the system is n,nn;»g. We recommend that a qualified person and/or company be selected to guarantee and be responsible for any freon loss during the change of the buckeY traps. b) Replacement of Motor Contactor Contacts - These aze original and have seen the wear and tear over the last 24 years. The contacts eventually lose the ability to do their job properly. The contacts aze parts that start the motors on the soleniods. The soleniods tell the refrigeration system when to let freon through the system and when to shut it off. c) Replacement of Snow Melt Recirculation Pump - T�is pursp keeps the hot gas moving through the coiis in the saow melt p:t. The pit melts the snow that is dumped by the Resurfacer. The current pump l�as not worked for 6 months. If we would replace this pump we would reduce our head pressure on the refrigeration system and the snow in the pit would melt faster. Ttrerefore, we would not have to waste hot water to melt the snow. 4) Evaporative Condenser —(not included in the January 11, 1998 bid packa$e) Replace existing unit with 150-Yon aapacity uniY (also known as Cooling Tower, Tower, Condenser or Evap Unit). The condenser is made up of two sections; one section is the motors and the second is the evaporative coils. The motor section is original and has a maximum capacity to handle 135 tons. The evaporative section is 20 yeazs old and is scaled with calcium build-up about'/4 inch thick. We cannot say when this unit will expire, but we can give you some information as far as efficiency, tonnage and scenarios from other communities. Our current set-up has the least amount of efficiency for two reasons; scale build-up and tonnage capacity. How can we conect this? 1) Scaling occurs when the water that is used to cool down the hot gas, runs over the coils that the freon gas passes through. Over time the water creates a build-up of calcium on the coil tubing. When scale is present it reduces the waters ability to cool the freon gas back into liquid freon. When the gas can not be turned back into liquid, it leads to high pressure and uhimately shuts down the system because it over-heats. The easiest example the Staff can give you is this: The condenser unit is nothing more than a radiator, like your car, it reduces the temperature. The scale is compazable to someone putting a piece of cardboard in front of their radiator with a four-inch hole in it. You find that it works when it is -20° but your car will overheat when it is 40° - 90° outside. Basically, you are insulating your radiator. The same is true with ihe cooling tower, a.nd the scale is tke insulator. There is not enough surface area to cool the hot gas down into a liquid. The same is true with your caz, if it over-heats; it is bringing hoY anYi-freeze into the radiator. The radiator is supposed to cool the anti-freeze and then retum it into the engine, but if the cardboazd is there, it cannot do the job as it gets wanner outside. In 1979, the former Manager had the same problem. Staff thought that they could chisel, scrape or break off the scale build-up by hand. The reason rt cannot be done is because the tubing is very sensitive. If you put a nick or pin hole in the tubing, eventually the freon passing through the tubing wIll fmd the nick or pinhole and eat away at that area. This same thing basically happens in the floor. Freon will attack any void or impurity in the tubing. In 1979 the City had to replace the coil section of the tower because the Staff damaged the tubing. We have currently implemented an aggressive water treatment program to counteract the scaling problem This needs to be done with an e�sting tower or a new tower if and when one would be put in place. However, we may never be able to reduce the scale enough to have the tower operate properly and the way it was intended. The scale problem started the first year it was in operation. It has progressively gotten worse over the years. 2) The compressors that operate our system require a minimum of 135 tons of capacity for the evaporative condenser. With our current tower, having a masimum output of 135 tons, this leaves no room for enor. Generally speaking a 135-ton unit does not guarantee thaY you will get the full 135 tons of capacity. There are many factors that dictate how a tower will work. Factors are; suction pressure, dischazge pressure, wet bulb temperature and scale build-up. Typically, a system such as ours uses a 150-ton capacity cooling tower. At the present time we aze unable to run our second compressor more than a few minutes before the refrigeration system shuts down due to over-heating. This is due to all of the factors stated above. To operate the refrigeration system efficiently and effectively, we would suggest ine*easazg tlxe evaporative condenser Yo a 150-ton capacity. 3) Hopkins, MN has replaced their evaporative condenser three times in the last 15 years. Cottage Cnove has replaced the coil section once in 24 years. New Hope, MN and North St. Paul, MN have replaced their towers in the past 10-15 years. We believe that the life expectancy of our tower is a direct reflection of how it has been maintained. 0 GENERAL SUMMARY OF COSTS A. Replacement ofFloor - $189,000.00 B. Install New Freon Float Control -$9,000.00 C. Replace Bucket Traps - Replace Contactor Contacts - Replace Snow Melt Recirculation Pump —$5,000.00 D. Replace Evaporative Condenser - $25,000.00 Total Estimated Cost = $228,000.00 In the original bid process, CouncIl approved an inter-departmental loan from the Park Trust Fund in the amount of $125,000.00. The Motor Replacement, Freon Leak Detector and the E�aust Fan from the original bid were completed eazlier this yeaz with a cost of $17,507.00. This leaves the loan balance at $107,493.00. City staff still has to find $120,50'7.00 Yo complete the project using the estimated costs from above. Staffwould also request using Mr. Gary D. Kristofitz, Professional Engineer with Bonestroo and Associates, to prepare plans and specifications, set a bid date and authorize the advertising for the bids.