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Home My WebLink AboutReso 1980-10392 , - t rl'i I RESOLUTION NO. 10392 RESOLUTION OF THE CITY COUNCIL OF THE CITY OF CHULA VISTA ACCEPTING BIDS AND AWARDING CONTRACT FOR ACOUSTIC MATERIAL INSTALLATION IN PARK WAY COMMUNITY CENTER The City Council of the City of Chula Vista does hereby resolve as follows: WHEREAS, the City Council has heretofore authorized an acoustical study to improve the acoustics in Park Way Community Center, and WHEREAS, said study, made by San Diego Acoustics, Inc., recommends the. most cost-effective and best solution for improving the Center's acoustics is the installation of Tectum wall panels in the multipurpose room and Johns Manville Tempertone 360 ceiling tiles in the games, crafts and activities rooms, and WHEREAS, installation of the Tectum wall panels in the multipurpose room can best be done by an outside contractor, while the ceiling tiles in the games, crafts and activities rooms can best be installed by City forces, and WHEREAS, the following two informal bids were were received for installation of the Tectum wall panels in the multipurpose room: Spring Valley Installation Contractors Acoustic Specialties $7,995.00 8,466.00 and WHEREAS, it has been recommended that said contract be awarded to the lowest responsible bidder, Spring Valley Instal- lation Contractors, who has assured the City that they are a licensed contractor in the State of California and can produce an acceptable performance bond. I NOW, THEREFORE, BE IT RESOLVED that the City Council of the City of Chula Vista does hereby accept said two informal bids, and does hereby award the contract for the installation of the Tectum wall panels in the multipurpose room to Spring Valley Installation Contractors. BE IT FURTHER RESOLVED that the Mayor of the City of Chula Vista be, and he is hereby authorized and directed to execute said contract for and on behalf of the City of Chula Vista. Presented by Approved as to form by ~-0Y~ . R. Asmus, Acting Director George D. Lindberg, City torney of Parks & Recreation - ADOPTED AND APPROVED fIY THE CITY COUNCIL OF THE CITY OF CHll.A VISTA, CALIFORNIA, this I ~ 1 ,by the following IIOte, to-wit: 3rd day of Februorv AYES: NAVES: ABSTAIN: ABSENT: Ccxn:i1men McCandli<:;<:; Scott, Gillow. Hvil~ rnv Councilmen Ccx.rICilmen Councilmen None None None cJ~/(:{~ Mayor of the City of ChuIo Vista STATE OF CALIFORNIA ) COUNTY OF SAN DIEGO ) 55. CITY OF CHULA VISTA ) I, JENNIE M. FULASZ, CMC, CITY CLERK of the City of Chulo Vista, California, DO HEREfIY CERTIFY that the above and foregoing is a full, true and correct copy of RESOLUTlON NO. 10392 ,and that the same has not been amended or repealed. DATED City Clerk (seal) (O)~c rr_~~n ! I I'"'''''~''.'~.''''~' ~.tl)Yt" (~:iJ):! , ,,"'''\''~~1 SAN DIEGO ACOUSTICS, Inc. October 13 1930 Report No. 30-0190 Chula Vista P.0.113932 CHULA VISTA COMMUNITY CENTER Improvement of Acoustics INTRODUCTION San Diego Acoustics, Inc. was retained by the City of Chula Vista to make specific recommendations for the improvement of the acoustics in selected areas of the new Community Center on Park Way, Chula Vista. .. The rooms in question are the Multipurpose Auditorium (101); the Activities Room (113); the Crafts Room (112); and the Games Room (111). These rooms all have different purposes but suffer from the same defect of being over-reverberant. The existing conditions were calculated, the effect of a number of acoustical materals was examined and a solution for the problems of each area has been found. TERMS, SYMBOLS AND FORMULAE A number of terms, symbols and formulae are used in this report and the following brief explanation is offered. Sound absorption is the effect of noise reduction by "soaking it up" and converting it to heat. The amount of sound absorption is measured in "Sabins". One Sabin is represented by 1 square foot of material which absorbs all, or 100%, of sound striking it. Such a material is said to have a "sound absorption coefficient" (a) of 1.00, One Sabin may also be obtained by having 2 square feet of a material having an a of 0.50. The area of an absorber is usually denoted by the letter S and the total absorption (in Sabins) by A. The relationship between the two is given by A = S x a (Sabins) { 0 ')q ~ 600 B STREET. SUITE 1130 . SAN DIEGO, CALIFORNIA 92101 . (714)231-8986 Report No. 80-0190 I Page 2 of 7 Each material will absorb sound differently at different frequencies. As a general rule, the a of a material is measured at 6 different frequencies in a band one octave wide (an octave is a doubling of frequency) starting at 125 Hz (Hz is short for "Hertz" or "cycles per second") and finishing at 4000 Hz. (The human voice covers the range 200 to 2000 Hz). Four of the six a values are sometimes com- bined into a single number known as the NRC or Noise Reduction Coef- ficient but this is not used in this report. The acoustical quality of a room is judged mainly by how long sound takes to die away or "decay". The decay time is given the symbol t60 which denotes the time in seconds for a sound to diminish to one millionth of its original value (60 decibels). Too short a decay time makes a room sound "dead" and too long a t60 makes the room "live"; sound becomes jumbled and speech becomes unintelligible. The decay time is determined by the volume of the room (V), the area of its surfaces and the absorption coefficient of the materials in the rooms. The relationship between these quantities is 0.049 x V t60 = S,a, + S2a2 + S3a3 .... seconds where S" S2, S3 .... and a"a2 and a3denote the respective surface areas and absorption coefficients of walls, windows, doors, etc. EXISTING CONDITIONS The Community Center was visited on October 2, 1980. Each room was examined t~ assess its particular problem and a set of drawings was obtained. Subsequently the acoustical qualities of each room was calculated. Note that throughout the analysis the Activities Room and the Crafts Room have been treated identically. Although there are some minor difference in size, shape, etc., they are sufficiently close both in dimensions and use to be considered identical. The results of the calculations are shown in Table 1. Table 1 - Existing Reverberation Decay Times - seconds Octave Band Center Frequencv - Hz Room 125 250 500 1000 2000 4000 Mult i purpose 1.6 4.2 7.8 9.9 6.1 4.9 Activities/Crafts 0.7 2.0 3.8 4.8 1.8 2.4 Games 0.9 2.4 4.4 5.6 3.4 2.8 { 03Q2- Report No. 80-0190 Page 3 of 7 A number of conclusions may be drawn from these results. Obviously the decay times are far too long for satisfactory speech intelligi- bility. This defect is most marked in the mid to high frequency range because typical framing/drywall construction tends to absorb low frequency sound. DESIGN GOALS Each room has a different use and the proposed acoustical treatment must be designed to achieve an optimum decay time for that particu- lar use. The decay times for various uses are normally optimized around the 500 to 1000 Hz bands (the mi.ddle of the speech range). Table 2 below shows the normally acceptable range for the different uses and the values chosen for the Community Center. Tab1e 2 - Design Goa1s for Acceptab1e Reverberation Decay Times t60 seconds at 500Hz Room Use Room Range Chosen General Purpose - Multi purpose 1.6 to 1.9 1.7 Auditorium Lecture and Activities/ 0.6 to 1.4 1.0 Conference Cra fts Genera 1 Purpose - Games 1.4 to 1.8 1.8 Small REcm1~lENDATIONS The Multipurpose Auditorium It was requested by the City of Chula Vista that the acoustical treat- ment be confined to a band 14 feet wide running around all of the walls starting at a height of 8 feet from the floor. Because of the nature of the games played in the room when used as a court, the acoustical treatment must also be capable of withstanding physical abuse. Accordingly, three types of product were evaluated. The calculations were re-iterated until the amount of treatment necessary to achieve a good acoustical quality was achieved. The l 0) g z- --..--- Report No. 80-0190 Page 4 of 7 products chosen for evaluation were 1. "Tectum" Wall Panels 2. "Alpro" Acoustical Wall Panels 3. "Eckoustic" Functional Panels Each product is described fully in the attached copies of literature and technical data sheets. The results of the calculations are shown in Table 3. Table 3 - Multipurpose Room, Treated. Reverberation Decay Times Octave Band Decay Times for each Product - seconds Center Tectum 1 A 1 pro 2 Eckoustic 3 Frequency - Hz 13' wide 14' wide 88 Panels (3800 ft2) (4100 ft2) (2200 ft2) 125 1.9 1.5 1.6 250 2.6 I 1.9 2.1 500 1.7' 1.7" 1.7' 1000 1.6 1.8 1.9 2000 1.7 1.7 1.9 4000 1.6 1.6 1.9 1" Thick Tectum on 1 x 3 furring strips at 24" o.c. with 3/4" thick, 3/4 lb/ft 3 fiberglass in the cavity. 2 Over 2 x 2 horizontal studs at 24" o.c. with l~" thick, ]!2 lb/ft3 fiberglass in the cavity. As supplied by the manufacturer. 3 " Matches chosen optimum value. All three of the treatments would be satisfactory acoustically and should be chosen for cost effectiveness. Both Tectum and Alpro must be used in conjunction with the furring strips and fiberglass. The Eckoustic panels need less area because they stand off from the wall and therefore absorb on both sides. 1 039 -Z- Report No. 80-0190 Page 5 of 7 The Activities and Crafts Rooms In these rooms, speech intelligibility must be high and there should be a comfortable "feel". A decay time of 1.0 seconds at 500 Hz was chosen for these rooms, a value in the middle of the optimum range. After several calculations it was clear that what was needed in these rooms was a standard 'ceiling tile bonded to the surface with a 1/8" air gap behind. This can be achieved by using a thick "mastic" adhesive - one blob in each corner of the tile - and making sure that the back of the tile does not come into hard contact with the drywall surface. Both rooms require 784 square feet of such treatment which suggests that the best place for it is the ceiling (816 square feet less protruberances). Table 4 shows the decay times in the rooms with 784 ft2 of either of the following tiles. 1. Johns-Manville. Temper Tone 360 or similar 2. Armstrong. Travertone "Colomar" or similar These are described in the attached data sheets. Table 4 - Activities/Crafts Rooms - Treated. Reverberation Decay Times Octave Band Center 125 250 500 1000 2000 4000 Frequency - Hz Decay time to 0 1.0 1.7 1.0 0.7 0.7 0.7 seconds Games Room This room is not quite so critical for speech intelligibility and the acoustical treatment is required as much to reduce the noise as anything else. A reverberation decay time of 1.8 seconds at 500 Hz was chosen as the appropriate maximum although it could be less. Here again, standard ceiling tile as specified for the Activities and Crafts Rooms vlill be ideal. This room requires 450 square feet to achieve the desired effect and this may be placed ei~her on the ceiling or spread around the top half of the walls or as a combina- tion of both. {6'?>97.- Report No. 80-0190 Page 6 of 7 SUMMARY OF ACOUSTICAL TREATMENT Multipurpose Room Tectum 1" thick pan~ls 13ft long all round the walls - total 3796 square feet. Furring strips 1" x 3" at 24" o.c. max. Fiberglass 3796 square feet, 3/4" thick, nominal 3/41b/ft3 Decorative top and base 2" x 2" wood strips Alpro - Decorative metal panels of choice 14 ft long all around the walls - total 4088 square feet Furring strips 2 x 2 at 24" o.c. max. Fiberglass 4088 square feet, ly," thick, nominal ly,l b/ft 3 Decorative top and base 2" x 2" wood strips ',' Eckoustic Functional Panels - 88 panels 10 ft long by 2y, ft wide spaced evenly around the top of the walls Activities/Crafts Ceiling Tiles, 784 square feet glued to ceiling with 1/8" air space behind Johns-Manville - Tempertone 360 Armstrong - Travertone "Colomar" Games Same treatment as Activities/Crafts except requires 450 square feet minimum and may be on the ceiling or high up on the walls or both. SUPPLl ERS The Ceiling Tiles, Fiberglass and Furring Strips should be readily obtainable from local building suppliers although the required pattern of ceiling tile may have to be ordered. The "Tectum", "Alpro", and "Eckoustic" products may have to be . ! LJ 59 "6 Report No. 80-0190 Page 7 of 7 ordered directly from the manufacturers (see 1 ist below). MANUFACTURERS IITectumll Gold Band Building Products (A National Gypsum Division) 2001 Rexford Road Charlotte, North Carolina 28211 For local representative, try \.1. 1. Somervi 11 e 338 Fairway Lane Placentia, California 92670 (213) 435-4465 (714) 528-1966 "Alpro" Alpro Acoustics Division Structural Systems Corporation P.O.Box 30460 New Orleans, Louisiana 70190 (504) 522-8656 {',- "Eckoustic" Eckoustic Division Eckel Industries, Inc. 155 Fawcett Street Cambridge, Massachusetts 02138 (617) 491-3221 Ceil i ng Til es Armstrong 9700 Flair Drive El Monte California 91721 (213) 579-0260 El Monte (213) 686-1940 Los Angeles Johns-Manville Greenwood Plaza Denver, Colorado 80217 (313) 770-1000 For local representative, try (213) 775-3451 (213) 564-6701 James C. Berry Acoustician ____ ,.c ,/ I) ....~r--. I . ~ f', . of\r..-,~~ ~'\ \,...,,-,~--.....:1-,-~~~~'1. ___ -- .------- ..-". ," / !039Z Form No. F-229 12/73 CERTIFICATE OF CITY/DIRECTOR OF FINANCE Certification of unappropriated Balance I HEREBY CERTIFY that the money required for the appropriation of funds for the purpose set forth in the attached resolution is available in the Treasury, or is anticipated to come into the Treasury, and is otherwise unappropriated. Amount $ Fund Purpose Bidder Director of Finance The City of Chula Vista Date By Certification of Unencumbered Balance I HEREBY CERTIFY that the indebtedness and obligation to be incurred by the contract or agreement authorized by the attached resolution can be incurred without the violation of any of the provisions of the Charter of the City of Chula Vista, or the Constitution or the laws of the State of California, that sufficient monies have been appropriated for the purpose of said contract, that sufficient monies to meet the obligations of the contract are actually in the Treasury, or are anticipated to come into the Treasury to the credit of the appropriation from which the same are to be drawn, and that said monies now actually in the Treasury, together with the monies anticipated to come into the Treasury, to the credit of said appropriation are otherwise unencumbered. Amount Not to Exceed $ 7,995.00 4/L~~ Director of Finance The City of Chula Vista Date 2/3/81 6l6-6l60-SBA02 By Dept./Activity Parks & Recreation Fund Purpose Award Contract for acoustic material installation in Park Way Comm. C1 Bidder Spring Valley Installation Contractors Certificate No. 34 L eJ39 ~ /(-1()3r~