The URL can be used to link to this page

Home My WebLink AboutCT 91-07; La Vercia Condominiums; Tentative Map (CT) (13)Report No. 9110 April 22, 1991 JAMES C. BERRY - ACOUSTICIAN 2401 Trace Road Spring Valley, CA 91978 (619) 660-0064 REPORT ON AN ACOUSTICAL STUDY 5 Unit Condominium Tamarack Avenue, Carlsbad Prepared for: A.R.C. Group 5751 Palmer Way, Suite H Carlsbad CA 92008 by: James C. Berry Acoustician James C. Berry - Acoustician Report No. 9110 (619) 660-0064 Page 1 REPORT ON AN ACOUSTICAL STUDY 5 Unit Condominium, Tamarack Avenue, Carlsbad INTRODUCTION The proposed 5 unit condominium project is located on the south side of Tamarack Avenue, east of Garfield Street and about 350 feet west of the Santa Fe Railroad tracks in the City of Carlsbad, California. The site is outside the 3 mile radius area of influence of McClellan Palomar Airport but is within 500 feet of a railroad right-of-way and close to an important street. A noise study is required under the Noise Control Act of 1973, Health and Safety Code 46000 et.seq.; the Planning and Zoning Law Government Code 65302 (f); CEQA Public Resource Code 2100 et.seq., and City of Carlsbad Policy No.17, in lieu of the updated Noise Element of the General Plan. EXISTING CONDITIONS The site has a 65 foot frontage along Tamarack Avenue and is ap- proximately 312 feet long. It is presently unoccupied with some shrubs and an empty house pad at the road end, while the remain- der is covered with long wild grasses (see partial Site Plan, Figure 1.) Tamarack Avenue is a two-lane street with a center double yellow line, no parking lane, gutter, curb or sidewalk at the site. The posted speed limit is 25 mph and the current traffic flow is 9,000 Average Daily Trips (ADT) between Jefferson Street and Carlsbad Boulevard (Source: SANDAG Map of Average Weekday Traffic Volumes, 1990 Edition.) The railroad tracks are owned by the Santa Fe Railroad but are jointly operated by Amtrak. There are sixteen scheduled Amtrak trains every day between San Diego and Los Angeles and return, fairly evenly spread out between about 6:15 a.m. and 10:45 p.m. at Carlsbad (source: Amtrak information.) There are two regu- larly scheduled freight trains per day, one in and one out, but there could also be one or two specials at various times (Source - Santa Fe Railroad Information.) Thus, between eighteen and twenty trains pass the site every day. James C. Berry - Acoustician Report No. 9110 (619) 660-0064 Page 2 The site was visited on Friday April 19, 1991, for familiarization purposes and to make noise measurements. Two measurement loca- tions were chosen. The first was 50 feet from the centerline of the nearest traffic lane on Tamarack Avenue (56 feet from the centerline of the right-of-way.) This location is indicated in Figure 1. The second location was 10 feet from the rear property line (approximately 300 feet from the road.) The measurements were made using a Quest Electronics Precision Integrating Sound Level Meter, Type 1800, which meets all applic- able U.S. and International Standards for Type 1 instruments (ANSI SI.4-1983; IEC 651-1979 and 804-1984.) The sound level meter was mounted on a tripod and fitted with a windscreen. The results of the measurements were as follows: Highest Level Lowest Level Average Duration Recorded Recorded Level Lmax-dB(A) Lmin-dB(A) Leq-dB(A) Min. 84* 38 60 31 75* 35 51 26 * Highest level caused by train whistle Noise levels created by passing trains were noted separately. At location 1, an Amtrak passenger train travelling south created a maximum level of 84 dB(A) due to the whistle while the engine and cars were much lower in level and passed in about 5 seconds. A Santa Fe freight train travelling north created 80 dB(A) due to the whistle, while the engine and various freight cars created noise levels in the range 65 to 75 dB(A) apparently due to the varying condition of wheels and axle bearings. It took almost 20 seconds to pass. At location 2, the whistle of a second, very short, freight train travelling north produced 75 dB(A) and, again, the train passed in 5 seconds. This lower level whistle was due to shielding from the existing apartment building to the east. The train noise is included in the measured Leq. James C. Berry - Acoustician Report No. 9110 (619) 660-0064 Page 3 The measurements for a half hour are representative of a typical weekday daytime hourly average noise level [Leq(hour)]. The relationship between the Leq(hour) and the long term community noise levels (CNEL or Ldn) has been found to be: CNEL/Ldn = Leq (hour) + 2 dB(A) Thus, at the two measurement locations the measured community noise levels were 62 and 53 dB(A) CNEL/Ldn respectively. Because of the ground surface, shrubs and grass, the attenuation constant is calculated at 12.5 times the logarithm to the base 10 of the ratio of the distances. It is further calculated that the 1991 noise contours will occur as follows: 65 dB(A) CNEL/Ldn - 32 feet from the centerline of Tamarack Ave. 60 dB(A) CNEL/Ldn - 81 feet from the centerline of Tamarack Ave. The existing 60 dB(A) contour is shown on Figure 1. FUTURE CONDITIONS WITHOUT PROJECT Even if the proposed project is not built, some future changes along Tamarack Avenue will result in corresponding changes in the noise levels. SANDAG is estimating that by the year 2010 the area will be built out and that Tamarack Avenue will be carrying 9,700 ADT (Source: SANDAG via Bob Johnson of the City of Carlsbad Traffic Engineering Departemnt.) In addition, Tamarack Avenue will be slightly realigned to bring the centerline 10 feet closer to the site. At measurement loca- tion 1, the noise level would rise by about 1 dB due to the reloca- tion of the centerline and just over 1/4 of a dB due to the rise in traffic. The future noise level at measurement location 1 would therefore be 63 dB(A) and the 60 dB(A) CNEL/Ldn contour would oc- cur at 81 feet from the new centerline of Tamarack Avenue. This theoretical contour is shown in Figure 1. IMPACTS DUE TO THE PROJECT Construction Noise Construction of the project will result in a significant but temporary noise impact on the surrounding community especially apartments directly to the east and west of the site and to houses across the street. There will be site preparation, grading, pav- ing, foundation laying, building erection and finishing. Typical appropriate equipment will be on site during the various phases of construction and, at completion, all of this equipment will be removed and the noise will cease. James C. Berry - Acoustician Report No. 9110 (619) 660-0064 Page 4 Project Noise The project will introduce 5 condominium dwelling units into a site having apartments each side, single family houses opposite, and residential development all around. The project will intro- duce no new or unusual noise sources into the area. The project could generate up to 50 ADT on to Tamarack Avenue. This represents less than 1/2 percent of the total projected traffic flow on Tamarack Avenue and will be acoustically insig- nificant. NOISE IMPACT ON THE PROJECT Exterior Noise As was shown above the 60 dB(A) CNEL/Ldn noise contour will theo- retically occur at a distance of 81 feet from the new centerline of Tamarack Avenue. The proposed building will modify the sound field. The noise level on the east and west sides of the building will drop by 3 dB(A) due to the 50 percent cutoff shielding of the structure. Thus, on both sides of the building, the noise level everywhere will be below 60 dB(A) CNEL/Ldn. At the north end of the building, there is a 6 foot high stucco wall and carports shielding the ground floor and backyard (see Figures 2 and 3.) The noise level at the ground floor facing the street will also be below 60 dB(A) CNEL/Ldn. The only part of the proposed building where noise levels will be above 60 dB(A) CNEL/Ldn is the north face of the second story im- mediately overlooking Tamarack Avenue, where the noise level will be slightly above 61 dB(A) CNEL/Ldn (Unit No.l.) At this eleva- tion, there is a balcony overlooking the street and a roof deck above (see Figure 4.) Interior Noise The noise reduction provided by typical Californian construction, i.e. wood framing, exterior stucco, interior drywall, R-ll insula- tion, and sliding glass doors and windows, is 25 to 30 dB(A) when all doors and windows are closed. (Source: County of San Diego Noise Element.) Thus, the noise level inside the living/dining room of Unit 1 will be in the range 31 to 36 dB(A) CNEL/Ldn, well in compliance with California Administrative Code, Title 24, and the City of Carlsbad requirements. James C. Berry - Acoustician Report No. 9110 (619) 660-0064 Page 5 MITIGATION Mitigation is required only at the balcony and roof deck of Unit No.l. The ground floor is shielded by a 6 foot high wall. If the City staff deem it necessary, the balcony and roof deck require shielding to the extent of 1 dB(A) on the north side. [It should be pointed out that the apartment buildings to the east (Nos.351 and 353 Tamarack Avenue) have balconies facing the street with NO acoustical shielding.] If mitigation is required, it is recommended that the north wall of the balcony and roof deck (as indicated on Figure 4) be at least 5 feet high. The west wall can be left as shown in the drawing. Since view is important, consideration might be given to using glass or plexiglass for the roof deck and balcony walls. No other mitigation is deemed necessary. SUMMARY Only a small portion of the site is currently impacted by noise levels in excess of 60 dB(A) CNEL/Ldn. Tamarack Avenue now carries 9,000 ADT which will rise to 9,700 ADT by buildout in the year 2010. A new alignment will move the centerline of Tamarack Avenue 10 feet closer to the site. The project will create significant but temporary construction noise. It will introduce no new or unusual noise sources into the area and the project-generated traffic noise will be insignifi- cant. Only the north face of the second story of the building will have exterior noise levels above 60 dB(A) CNEL/Ldn, here the noise level will be 61 dB(A) CNEL/Ldn. Interior noise levels will be well below 45 dB(A) CNEL/Ldn with doors and windows closed. If mitigation is deemed necessary, the balcony and roof deck of Unit No.l should have 5 foot high walls on the north side. C. Berry; Acoustician Alignment •75 Fee> 4o (t 0)Sro n r zi H- (0 C5 0 (0 rt to 25 O ftI Mttw. fay £3i rnrni 0) w 0 DO 1 0)O hj O t-f F. )OdwrtM-oH- 0) 3 1-fD ^Q tJc o^ ^(D ft w ao "2010 . CTi 0) H 3vo (D I pamo r enrt 10 A X c UNIT H- (D ^ T3 C O ^ ^05 ft VD I-1