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Home My WebLink AboutWS Item 01 - Gaylord Texan ITEM # MEMO TO: HONORABLE MAYOR AND MEMBERS OF THE CITY COUNCIL FROM: BRUNO RUMBELOW, CITY MANAGER 'J MEETING DATE: APRIL 7, 2009 SUBJECT: WORKSHOP ITEM - GAYLORD TEXAN RECOMMENDATION: Staff recommends the City Council discuss Gaylord Texan visual and acoustical screening walls for the cooling towers and take any action necessary. BACKGROUND INFORMATION: On September 16, 2008, Council approved CU08-17 for the Gaylord Texan outdoor pool expansion and events pad. This conditional use permit also included 30 foot tall visual and acoustical screening walls for the cooling towers. Gaylord proceeded with construction drawings, and submitted preliminary plans to staff for review. On February 3, 2009, Mr. Bennett Westbrook, Senior Vice President of Design, Development and Construction for Gaylord, spoke to Council in executive session about possible alternative designs to mitigate the noise and screen the view of the cooling towers. Mr. Westbrook stated that he believed motor and fan technology had been developed that could significantly reduce the noise level from the towers, and that landscape screening could be utilized that would provide a preferable screening solution to a 30 foot tall masonry wall. Mr. Westbrook asked that he be allowed to study possible alternatives, and agreed to come back with a proposal in approximately 60 days. On March 19, 2009, staff received documents from Mr. Westbrook regarding the results of the study. Gaylord employed acoustical consultants Wrightson, Johnson, Haddon and Williams (WJHW) to research the possible benefits of replacing fans and motors for the cooling towers. WJHW determined that the replacement of the existing fans with Low Sound Fans with a variable frequency drive (VFD) system would provide a noise reduction equal to or exceeding that which would be realized from a 30 foot tall screening wall. Specifically, the following conclusions were found: • Existing Cooling Tower Maximum Noise Level (per manufacturers specifications) to Center of Katie's Woods Road - 71 dBA • 30 Foot Tall Accoustical Screening Wall Noise Level Reduction - 5-6 dBA, resulting in 65 or 66 dBA at Katie's Woods Road R:W GENDA\04-07-09\wk040709.gaylord.doc 1 4/2/2009 11:07:51 AM • Noise Level Reduction from Implementation of Low Sound Fans and Variable Frequency Drive - 6 dBA, resulting in 65 dBA at Katie's Woods Road Additionally, as Gaylord is no longer planning to place the ICE! and event pavilion along Katie's Woods Road, Mr. Westbrook proposes to replace the previously approved landscaping and masonry screening wall with taller, more dense landscaping only to provide a visual screening element for the cooling equipment. Should Council feel comfortable with these alternates, staff will place the item on a future Site Plan Review Committee agenda. R:W GENDA\04-07-09\wk040709.gaylord.doc 2 4/2/2009 11:07:51 AM GAYLORD ENTER`!' iI 'If,9IstIr Bennett WestbrookStte orYiac Mextrient, clop mesa,heir,,' ' (.,,Ott?e doll March 19,2009 Mr.Scott Williams Development Director City of Grapevine 200 South Main Street Grapevine,TX 76051 RE: Gaylord Texan Cooling Towers—Alternative Plan for Sound Mitigation Dear Scott,. In 2008,an approximately 30 foot tall barrier sound wall around the existing cooling towers was proposed and approved to reduce sound.This barrier would provide an estimated 5 to 6 dB reduction from the existing sound levels.As we progressed through the more detailed research to complete the design,our engineering consultants(Huitt 2ollars)discovered several factors that would significantly hinder the construction of the proposed wall.The 30 foot height of the wall required substantial foundation supports that would extend 10 to 15 feet into the small area adjacent to the towers that already has a sanitary sewer line,a storm drain line and a gas line along with a 10 foot easement for a public water line.In addition,space is needed for maintenance vehicle access. As a result,we continued to look for an alternative solution that would provide similar sound reduction. Fortunately,our research led us to a new proposed alternative,which we believe is more advantageous for the city,neighbors and the environment. This proposed alternative consists of refitting the cooling towers with low sound fans and a variable frequency drive(VFD)system along with the installation of a landscape screen of trees along Red Bud Road and Katie's Woods Road.The VFD system controls the rotational speed of the electrical motors allowing a more efficient distribution of the cooling load and less sound generation.Our consultants report that installing the combination of low sound fans and the VFD system would provide an estimated 6 dB reduction from existing sound levels. This alternative solution not only provides equal or better sound reduction than the proposed wall;it has the added benefit of being friendlier to the environment.In addition to creating less sound,the VFD system and the low sound fans are expected to require less energy.The landscape screen of trees along Red Bud Road and Katie's Woods Road will visually enhance the natural setting in the area. If this alternative is approved,it will take approximately ten weeks to order and receive the equipment and an additional six weeks to complete the installation. Gaylord is prepared to begin this process immediately upon approval. We have attached a report from WJHW,our sound consultants,dated 3/19/2009 and summarizing their evaluation of the proposed alternative mechanical plan for sound mitigation along with a diagram of the proposed landscape screen. Thank you for your consideration in this matter. S' c rely, Mrif ./ Yr,er ennett Westbrook Gal-lord Entertainment Company One Gaylord Drive,Nashville,TN 37214 Telephone 615-31(,-6436 Facsimile 615,316-6557' main bieratbrookteg.lonientee'taintuentun! HVV.'- -- Wrightson,Johnson,Haddon&Williams,inc. Designers and Planners for Sound,Video,Multi-Media Telecommunications,Broadcast,Theatre&Acoustics Dallas • San Antonio March 19,2009 Mr. Al Beams Gaylord Entertainment Company One Gaylord Drive Nashville,TN 37214 Re: Gaylord Texan Cooling Towers Evaluation of Mechanical Plan for Sound Mitigation Dear Mr.Beams, The purpose of this document is to review the operation performance of the existing Gaylord Texan cooling towers,as well as analyze sound mitigation measures including the construction of a solid acoustical barrier wall and mechanical modifications to the towers. Sound levels given in this report are evaluated at Katie's Woods Road/Red Bud Wall based on the cooling towers operating at worst-case,maximum load conditions. Sound emission data incorporated into our analysis for the existing and the proposed alternative solutions was provided by the mechanical engineer. The sound levels in this document are based on data published by the cooling tower manufacturer.There are currently a total of eight cooling tower units installed for the Gaylord Texan.Six of these eight towers are capable of operating simultaneously with the remaining two reserved as alternates.Manufacturer sound data for the towers encompasses all six towers operating simultaneously under a maximum load.These worst-case operating conditions most often occur when the exterior ambient temperature is above 95-degrees Fahrenheit and the building achieves full occupancy. Since operable load conditions are reliant on exterior temperature and building occupancy,the towers would be operating under a lesser load during different times of the day and year.We anticipate that sound levels would correspond with these lesser load conditions and result in levels below those stated in this document. On-Site Sound Measurements On-site sound level measurements were conducted on February 26,2008 to quantify cooling tower sound at.Katie's Woods Road/Red Bud Road with a total of five of the eight towers operating at less than 100%capacity.Due to aircraft sound from DFW Airport, full 8-minute Leq measurements were not obtained per the City of Grapevine Sound Ordinance.However, one-minute Leq measurements were recorded and are considered representative of the cooling tower sound level experienced on site. The resulting sound levels measured were 64 to 65 MA at Katy's Woods Road/Red Bud Road. As the cooling towers were not operating at full capacity, we anticipate the sound level recorded to represent sound levels on cooler days and/or when Gaylord Hotel is not booked to capacity. 4801 Spring Valley Road,Suite 113 Dallas,TX 75244 972.934.3700 voice 972.934.3720 fax Page 2 of 3 19 March 2009 Gaylord Texan Mechanical Sound Review Mr.Al Beams Existing Conditions Manufacturer's specifications show that the six towers or cells operating at a maximum load of 100%would produce an overall sound level of 88 dBA at 23 ft. This calculates to approximately 71 dBA at 155 ft which is the approximate distance from the center of the cooling tower system to Katie's Woods Road/Red Bud Road. This level represents peak sound levels during the hottest days of the year and when the hotel is filled to capacity. Maximum loads would only occur when temperatures exceed 95-degrees Fahrenheit. Acoustical Barrier Wall As previously discussed and designed,sound levels may be mitigated by the construction of a solid acoustical barrier wall(EIFS structural wall) in close proximity to the cooling towers. An acoustical barrier wall with an approximate 30-ft height,as developed during our initial sound mitigation exercise,would provide an estimated 5 to 6 dB reduction from the existing levels resulting in a sound level of approximately 65 dBA at Katie's Woods Road/Red Bud Road when six towers are operating at 100%capacity. This reduction would provide a clearly noticeable perceptible decrease from the existing cooling tower sound level. Proposed Mechanical Solution The Proposed Mechanical Solution incorporates the installation of Low Sound Fans with a variable-frequency drive(VFD) system.This alternative solution would allow the cooling tower system to operate more efficiently and decrease overall sound emission levels.These modifications would cause the towers to produce an overall sound level of 82 dBA at 23 ft when six fans are operating at 100%fan speed. This calculates to approximately 65 dBA at Katie's Woods Road/Red Bud Road.This alternative,including the installation of both Low Sound Fans and a VFD system,would result in a 6 dB reduction from the existing condition at Katie's Woods Road/Red Bud Road and provide a clearly noticeable perceptible decrease from the existing cooling tower sound level. Table 1 provides a comparison of existing,unmitigated conditions versus each of the proposed mitigation measures with all six cooling towers operating under a worst-case maximum load. Table 1:Worst-case Cooling Tower Sound Level Comparisons Difference in Existing Condition Sound Level at Katie's Cooling Tower Configuration d (dBA) vs.Proposed Mitigation Measures Road Woo (dBA) Existing,unmitigated 71 -- Acoustical Barrier Wall 65 -6 Proposed Alternative Solution 65 Conclusions The results of this analysis show that the existing,unmitigated cooling towers operating under worst-case,maximum load conditions would result in an approximate sound level of 71 dBA at Katie's Woods Road/Red Bud Road. The acoustical barrier wall and proposed alternative Wrightson,Johnson,Haddon&Williams,inc. Designers and Planners for Sound,Video,Multi-Media, Telecommunication,Broadcast,Theatre&Acoustics Page 3 of 3 19 March 2009 Gaylord Texan Mechanical Sound Review Mr.Al Beams solution operating under the same maximum load conditions would both provide a 6 dB sound reduction from the existing,unmitigated condition at the same location. Since the load conditions of the cooling towers would be less during different times of the day and year due to temperature and occupancy, it is estimated that these approximate sound levels would be less than those estimated in Table 1 above.It is typical that the load of a cooling tower system be adjusted and redistributed with some units operating under a higher load than others. As discussed,it is probable that additional sound reduction could be accomplished by this redistribution along with the Low Sound Fans and VFD system described as part of the Proposed Alternative Solution. I trust this information to be helpful.Please feel free to contact me directly with questions or if we can provide additional information. Sincerely, Wrightson,Johnson,Haddon,&Williams,Inc. Kyle Matthis Designer Cc: Ginger 'chucite Gaylord Ron Baker WJHW Wrightson,Johnson,'Haddon&Williams,Inc. Designers and Planners for Sound,Video,Multi-Media, Telecommunication,Broadcast,Theatre&Acoustics , ....— V) . 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