42428 Chisolm Trail, Murrieta CA 92562 phone 760-473-1253 www.ldnconsulting.net fax 760-689-4943
5/13/22 21-90 UDSP Noise Letter
1 May 13, 2022
Sophia Habl Mitchell
Sophia Mitchell & Associates
P.O. Box 1700
Gualala, CA 95445
RE: Noise Analysis Letter – USDP Amendment in San Marcos CA
The purpose of this letter is to analyze the noise impacts associated with the proposed University District Specific Plan Amendment (UDSPA). The proposed University District Specific Plan Amendment (UDSPA) proposes changes in the development intensity of several uses within the University District Specific Plan (UDSP) area. The UDSPA also expands the existing UDSP planning area by approximately 8 acres. The revised traffic volumes are a result of changes to various land uses and zoning.
The proposed University District Specific Pl an Amendment (UDSPA) calls for the development of 2,850 mixed-use residential units, 550 student housing units, 250 hotel room, 920,000 s.f. of general office, 200,000 s.f. of medical office, 345,000 s.f. of mixed use retail/commercial, 5,000 s.f. of community/civic uses as well as parks/ open space, urban trails/paths, preserve open space and public streets. A general land use comparison between the currently approved UDSP and the proposed is shown in Table 1.
Table 1: UDSPA Changes
Use Current UDSP (UDSP)
Approx. 194 acres
Proposed Project
(UDSPA)
Approx. 202 acres
Change
Mixed-use Residential 2,600 units 2,600 units No change Student Housing 800 units 800 units No change
Hotel 450 rooms 250 rooms -200 rooms
General Office 638,000 sf 920,000 sf +282,000 sf
Medical Office 300,000 sf 200,000 sf -100,000 sf
Mixed Use Retail/Commercial 700,000 sf 345,000 sf -355,000 sf Community/Civic 5,000 sf. 5,000 sf -25,000 sf
Parks/Paseo/Plaza and Urban Opens Space 25.00 acres 27.13 acres to
31.13 acres (1)
+2.13 acres
to +6.13
acres
Urban Trails/Paths 850 students 850 students No change
Preserved Open Space (Habitat) 1.38 acres 1.38 acres No change Public Streets 15.10 acres 15.10 acres No change
Sophia Habl Mitchell
Sophia Mitchell & Associates
P.O. Box 1700
Gualala, CA 95445
42428 Chisolm Trail
Murrieta CA 92562
phone 760-473-1253
5/13/22 21-90 UDSP Noise Letter
2 The UDSP also allows for a K-6 elementary school within the Residential Neighborhood. If the K-6 elementary school is constructed, there will be no resulting decrease in the allowed number of Mixed-Use Residential dwelling units. The units that would have been constructed in the area of the potential school site will be absorbed into the residential dwelling units proposed elsewhere within the project boundary. The traffic reports used in this analysis assumes the school would be built. Thus, a conservative case of 3,400 residential units and an elementary school are considered in this analysis.
Offsite Project Related Transportation Noise Levels
The offsite project related roadway segment noise levels projected in this report were calculated using the methods in the Highway Noise Model published by the Federal Highway Administration (FHWA Highway Traffic Noise Prediction Model, FHWA-RD-77-108, December 1978). The FHWA Model uses the traffic volume, vehicle mix, speed, and roadway geometry to compute the equivalent noise level. A spreadsheet calculation was used which computes equivalent noise levels for each of the time periods used in the calculation of Ldn. Weighting these equivalent noise levels and summing them gives the Ldn for the traffic projections. The noise contours are then established by iterating the equivalent noise level over many distances until the distance to the desired noise contour(s) are found.
Because mobile/traffic noise levels are calculated on a logarithmic scale, a doubling of the traffic noise or acoustical energy results in a noise level increase of 3 dBA. Therefore, the doubling of the traffic volume, without changing the vehicle speeds or mix ratio, results in a noise increase of 3 dBA. Mobile noise levels radiate in an almost oblique fashion from the source and drop off at a rate of 3 dBA for each doubling of distance under hard site conditions and at a rate of 4.5 dBA for soft site conditions. Hard site conditions consist of concrete, asphalt, and hard pack dirt, while soft site conditions exist in areas having slight grade changes, landscaped areas, and vegetation. The future traffic noise model utiliz es a typical City vehicle mix 96% Autos, 2% Medium Trucks, and 2% Heavy Trucks for all analyzed roadway segments.
Community noise level changes greater than 3 dBA are often identified as audible and considered potentially significant, while changes less than 1 dBA will not be discernible to average residents.
In the range of 1 to 3 dBA, residents who are very sensitive to noise may perceive a slight change.
There is no scientific evidence available to support the use of 3 dBA as the significance threshold; community noise exposures are typically over a long time period rather than the immediate comparison made in a laboratory situation. Therefore, the level at which changes in community noise levels become discernible is likely greater than 1 dBA, and 3 dBA appears to be appropriate for most people.
Sophia Habl Mitchell
Sophia Mitchell & Associates
P.O. Box 1700
Gualala, CA 95445
42428 Chisolm Trail
Murrieta CA 92562
phone 760-473-1253
5/13/22 21-90 UDSP Noise Letter
3 For the purposes of this analysis, a direct roadway noise impacts would be considered significant if the project increases noise levels for a noise sensitive land use by 3 dBA Ldn and if the project increases noise levels above an unacceptable noise level per the City’s Noise Compatibility Guidelines. The proposed project is expected to be completed in the year 2035, therefore, traffic numbers of Year 2035 with project were compared to traffic numbers of Year 2030 without project.
To determine if direct offsite noise level increases associated with the development of the proposed project will create noise impacts, the noise levels for the Year 2030 without project were compared with the noise level changes for the Year 2035 with the project contributions. The Year 2030 traffic numbers without project were taken from the originally approved University District Traffic Impact Assessment (RBF 2009). Updated traffic volumes for the Year 2035 are provided by the project’s traffic assessment (Urban Systems Associates, Inc., 2022) and reflect various changes to the project’s land uses per the UDSP Amendment. Noise contours were developed for the following traffic scenarios:
Year 2030 without project: Future year noise conditions without construction of the project per the original noise analysis provided by Investigative Science and Engineering, Inc.
Year 2035 with project: Future year noise conditions plus the completion of the project.
Year 2035 without project vs. Year 2035 Plus Project: Comparison of the project related noise level increases.
The noise levels for the roadways in the vicinity of the project site are given in Table 2 for the Year 2030 without and with Project and in Table 3 for the Year 2035 without and with Project Scenario.
Table 4 presents the comparison of the Year 2030 without project related noise levels and Year 2035 with project related noise levels. Note that the values given do not take into account the effect of any noise barriers, structures, or topography that may further reduce roadway noise levels.
Due to changes in land use per the UDSP Amen dment, various road segments may or may not have been analyzed for both 2030 and 2035 scenarios. Where Year 2035 traffic numbers are not available for comparison, Year 2030 without proj ect was compared to Year 2030 with Project scenario.
Based on Table 4, the overall roadway segment noise levels will increase up to 1.8 dBA Ldn with the development of the proposed project. Additionally, noise levels are expected to decrease along several roadway segments due to an overall reduction in vehicular trips and a redistribution of traffic with removal of the SR-78 flyover. The proposed project does not create a direct noise increase of more than 3 dBA Ldn on any roadway segments. Therefore, the proposed project’s direct contributions to off-site roadway noise increases will not cause any significant impacts to any future noise sensitive land uses.
Sophia Habl Mitchell
Sophia Mitchell & Associates
P.O. Box 1700
Gualala, CA 95445
42428 Chisolm Trail
Murrieta CA 92562
phone 760-473-1253
5/13/22 21-90 UDSP Noise Letter
4 Table 2: Year 2030 Noise Levels with out vs with Project (Approved UDSP) Roadway Segment
UDSP UDSP + Project
ADT1
Noise Level @
50-Feet
(dBA Ldn)
ADT1
Noise Level @
50-Feet
(dBA Ldn)
Mission Road
Las Posas Rd to Knoll Rd 22,000 72.7 24,100 73.1
Knoll Rd to Pico Ave 20,800 72.4 19,500 72.1
East of Vineyard Rd 29,100 73.9 31,400 74.2
San Marcos Blvd
Rancho Santa Fe Rd to Discovery St 36,842 74.9 52,400 76.4 Discovery St to Las Posas Rd 50,600 76.3 50,700 76.3
Las Posas Rd to Via Vera Cruz 40,300 75.3 41,200 75.4
Via Vera Cruz to Bent Ave 43,700 75.6 45,200 75.8
Bent Ave to Grand Ave 49,900 76.2 51,400 76.3
Grand Ave to SR-78 EB Ramps 67,400 77.5 64,100 77.3
SR-78 WB Ramps-Knoll Rd to Westlake Dr 37,700 75.0 38,100 75.0 Westlake Dr to Pico Ave 35,600 74.8 40,000 75.3
Pico Ave to Twin Oaks Valley Rd 29,900 74.0 33,500 74.5 Twin Oaks Valley Rd to Rancheros Dr 26,200 73.4 30,300 74.1 Knoll Rd to Westlake Dr - - - -
Discovery St
San Marcos Blvd to Discovery St/La
Sombra Dr 13,000 70.4 29,100 73.9
Discover St/La Sobra Dr to Via Vera Cruz 13,200 70.4 14,000 70.7 Via Vera Cruz to Bent Ave/Craven Rd 19,600 72.2 14,500 70.9 Bent Ave/Craven Rd to Grand Ave 14,400 70.8 21,200 72.5 Grand Ave to Street “A” 31,200 74.2 18,600 71.9
Street “A” to Rush Dr 28,000 73.7 28,700 73.8
Rush Dr to Twin Oaks Valley Rd 29,800 74.0 26,200 73.4
Bent Ave
Grand Ave to San Marcos Blvd 8,800 68.7 8,400 68.5
San Marcos Blvd to Discover St 11,100 69.7 11,900 70.0
Craven Rd
Discovery St to Foxhall Dr 16,200 71.3 17,000 71.5
Echo Ln to Rush Dr 16,200 71.3 17,000 71.5
Rush Dr to Twin Oaks Valley Rd 17,200 71.6 20,500 72.4
East of Twin Oaks Valley Rd - - - -
Rush Dr
Craven Rd to Discovery St 7,800 68.2 14,700 70.9
1 Source: University District Traffic Impact Assessment (RBF 2009)
Sophia Habl Mitchell
Sophia Mitchell & Associates
P.O. Box 1700
Gualala, CA 95445
42428 Chisolm Trail
Murrieta CA 92562
phone 760-473-1253
5/13/22 21-90 UDSP Noise Letter
5 Table 2 (Cont.): Year 2030 Noise Levels without vs with Project (Approved UDSP) Roadway Segment
UDSP UDSP + Project
ADT1
Noise Level @
50-Feet
(dBA Ldn)
ADT1
Noise Level @
50-Feet
(dBA Ldn)
Twin Oaks Valley Rd
South of Village Dr 38,200 75.1 42,300 75.5
Village Dr to Craven Rd 43,900 75.7 48,800 76.1
South of Barham Dr 37,200 74.9 41,300 75.4
Discovery St to Carmel St 50,900 76.3 49,700 76.2
SR-78 WB Ramp to Civic Ctr Plaza Dwy 58,400 76.9 58,200 76.9 Civic Ctr Plaza Dwy to San Marcos Blvd 41,700 75.4 42,200 75.5 San Marcos Blvd to Richmar Ave 42,200 75.5 44,800 75.8
Richmar Ave to Borden Rd 29,400 73.9 34,500 74.6
Barham Dr
Twin Oaks Valley Rd to Campus Wy 27,800 73.7 28,400 73.8 Campus Wy to Industrial St 36,400 74.8 27,600 73.6
La Moree Rd to Warplex Ave 31,900 74.3 33,800 74.5
Warplex Ave to Woodland Pkwy 32,600 74.4 36,700 74.9
East of SR-78 EB Ramp - - - -
Las Posas Rd
SR-78 to Grand Ave 50,200 76.2 49,400 76.2
Via Vera Cruz
Grand Ave to Linda Vista Dr 16,400 71.4 17,000 71.5
Linda Vista Dr to San Marcos Blvd 13,900 70.7 14,700 70.9 Grand Ave
Las Posas Rd to Via Vera Cruz 27,700 73.7 27,200 73.6
Bia Vera Cruz to Bent Ave 18,300 71.9 18,200 71.8
Bent Ave to San Marcos Blvd 13,500 70.5 13,300 70.5
San Marcos Blvd to Discovery St 22,700 72.8 22,500 72.8 Knoll Rd
Mission Rd to Los Vallecitos Blvd 14,100 70.7 17,800 71.7 Los Vallecitos Blvd to San Marcos Blvd 16,700 71.5 16,100 71.3 Westlake Dr
North of San Marcos Blvd 3,500 64.7 10,400 69.4
South of San Marcos Blvd - - 28,900 73.8
Pico Ave
Mission Rd to San Marcos Blvd 10,100 69.3 10,000 69.2
1 Source: University District Traffic Impact Assessment (RBF 2009)
Sophia Habl Mitchell
Sophia Mitchell & Associates
P.O. Box 1700
Gualala, CA 95445
42428 Chisolm Trail
Murrieta CA 92562
phone 760-473-1253
5/13/22 21-90 UDSP Noise Letter
6 Table 3: Year 2035 Noise Levels without vs with Project (UDSP Amendment) Roadway Segment
UDSPA UDSPA + Project
ADT1
Noise Level @
50-Feet
(dBA Ldn)
ADT1
Noise Level @
50-Feet
(dBA Ldn)
Mission Road
Las Posas Rd to Knoll Rd - - - -
Knoll Rd to Pico Ave - - - -
East of Vineyard Rd - - - -
San Marcos Blvd
Rancho Santa Fe Rd to Discovery St 36,842 74.9 43,715 75.6 Discovery St to Las Posas Rd - - - -
Las Posas Rd to Via Vera Cruz - - - -
Via Vera Cruz to Bent Ave - - - -
Bent Ave to Grand Ave 37,845 75.0 37,845 75.0
Grand Ave to SR-78 EB Ramps - - - -
SR-78 WB Ramps-Knoll Rd to Westlake Dr - - - -
Westlake Dr to Pico Ave - - - -
Pico Ave to Twin Oaks Valley Rd - - - -
Twin Oaks Valley Rd to Rancheros Dr - - - -
Knoll Rd to Westlake Dr 24,141 73.1 24,151 73.1
Discovery St
San Marcos Blvd to Discovery St/La
Sombra Dr 18,608 71.9 23,120 72.9
Discover St/La Sobra Dr to Via Vera Cruz 18,540 71.9 23,120 72.9 Via Vera Cruz to Bent Ave/Craven Rd 17,725 71.7 22,953 72.8 Bent Ave/Craven Rd to Grand Ave - - - -
Grand Ave to Street “A” - - - -
Street “A” to Rush Dr - - - -
Rush Dr to Twin Oaks Valley Rd 14,410 70.8 24,294 73.1
Bent Ave
Grand Ave to San Marcos Blvd - - - -
San Marcos Blvd to Discover St 11,023 69.7 11,444 69.8
Craven Rd
Discovery St to Foxhall Dr 12,861 70.3 12,956 70.4
Echo Ln to Rush Dr 12,719 70.3 12,956 70.4
Rush Dr to Twin Oaks Valley Rd 12,806 70.3 13,134 70.4
East of Twin Oaks Valley Rd 10,113 69.3 10,200 69.3
Rush Dr
Craven Rd to Discovery St 1,908 62.0 2,500 63.2
1 Source: Project Traffic study prepared by Urban Systems Associates, Inc., 2022
Sophia Habl Mitchell
Sophia Mitchell & Associates
P.O. Box 1700
Gualala, CA 95445
42428 Chisolm Trail
Murrieta CA 92562
phone 760-473-1253
5/13/22 21-90 UDSP Noise Letter
7 Table 3 (Cont.): Year 2035 Noise Levels without vs with Project (UDSP Amendment) Roadway Segment
UDSPA UDSPA + Project
ADT1
Noise Level @
50-Feet
(dBA Ldn)
ADT1
Noise Level @
50-Feet
(dBA Ldn)
Twin Oaks Valley Rd
South of Village Dr 21,817 72.6 24,312 73.1
Village Dr to Craven Rd 21,973 72.7 24,312 73.1
South of Barham Dr 31,240 74.2 35,021 74.7
Discovery St to Carmel St 26,286 73.4 44,646 75.7
SR-78 WB Ramp to Civic Ctr Plaza Dwy 38,279 75.1 49,140 76.2 Civic Ctr Plaza Dwy to San Marcos Blvd 32,941 74.4 43,798 75.7 San Marcos Blvd to Richmar Ave 34,899 74.7 41,769 75.4
Richmar Ave to Borden Rd 24,111 73.1 28,308 73.8
Barham Dr
Twin Oaks Valley Rd to Campus Wy 12,705 70.3 21,053 72.5 Campus Wy to Industrial St 13,401 70.5 18,200 71.8
La Moree Rd to Warplex Ave 13,665 70.6 18,559 71.9
Warplex Ave to Woodland Pkwy 13,665 70.6 18,559 71.9
East of SR-78 EB Ramp 13,665 70.6 18,559 71.9
Las Posas Rd
SR-78 to Grand Ave Not Analyzed in the proposed UDSPA Traffic Study Via Vera Cruz
Grand Ave to Linda Vista Dr Not Analyzed in the proposed UDSPA Traffic Study Linda Vista Dr to San Marcos Blvd Grand Ave
Las Posas Rd to Via Vera Cruz
Not Analyzed in the proposed UDSPA Traffic Study Bia Vera Cruz to Bent Ave Bent Ave to San Marcos Blvd
San Marcos Blvd to Discovery St
Knoll Rd
Mission Rd to Los Vallecitos Blvd Not Analyzed in the proposed UDSPA Traffic Study Los Vallecitos Blvd to San Marcos Blvd Westlake Dr
North of San Marcos Blvd Not Analyzed in the proposed UDSPA Traffic Study South of San Marcos Blvd Pico Ave
Mission Rd to San Marcos Blvd Not Analyzed in the proposed UDSPA Traffic Study 1 Source: Project Traffic study prepared by Urban Systems Associates, Inc., 2022
Sophia Habl Mitchell
Sophia Mitchell & Associates
P.O. Box 1700
Gualala, CA 95445
42428 Chisolm Trail
Murrieta CA 92562
phone 760-473-1253
5/13/22 21-90 UDSP Noise Letter
8 Table 4: Approved UDSP vs. Proposed UDSPA Related Noise Levels Roadway Segment
UDSP UDSP Amendment 2030 vs 2035 +
Project
(dBA Ldn)1 2030 2030 +
Project 2035 2035 +
Project
Mission Road
Las Posas Rd to Knoll Rd 72.7 73.1 - - 0.4
Knoll Rd to Pico Ave 72.4 72.1 - - -0.3
East of Vineyard Rd 73.9 74.2 - - 0.3
San Marcos Blvd
Rancho Santa Fe Rd to Discovery St 74.9 76.4 74.9 75.6 0.7 Discovery St to Las Posas Rd 76.3 76.3 - - 0.0
Las Posas Rd to Via Vera Cruz 75.3 75.4 - - 0.1
Via Vera Cruz to Bent Ave 75.6 75.8 - - 0.2
Bent Ave to Grand Ave 76.2 76.3 75.0 73.9 -2.3
Grand Ave to SR-78 EB Ramps 77.5 77.3 - - -0.2
SR-78 WB Ramps-Knoll Rd to Westlake
Dr 75.0 75.0 - - 0.0
Westlake Dr to Pico Ave 74.8 75.3 - - 0.5
Pico Ave to Twin Oaks Valley Rd 74.0 74.5 - - 0.5
Twin Oaks Valley Rd to Rancheros Dr 73.4 74.1 - - 0.7
Rancheros Dr to Missions Rd 73.2 73.9 - - 0.7
Knoll Rd to Westlake Dr - - 73.1 71.9 -1.2
Discovery St
San Marcos Blvd to Discovery St/La
Sombra Dr 70.4 70.7 71.9 71.7 1.4
Discover St/La Sobra Dr to Via Vera
Cruz 70.4 70.9 71.9 71.7 1.3
Via Vera Cruz to Bent Ave/Craven Rd 72.2 72.5 71.7 71.7 -0.4 Bent Ave/Craven Rd to Grand Ave 70.8 71.9 - - 1.1
Grand Ave to Street “A” 74.2 73.8 - - -0.4
Street “A” to Rush Dr 73.7 73.4 - - -0.3
Rush Dr to Twin Oaks Valley Rd 74.0 73.2 70.8 72.0 -2.0 Bent Ave
Grand Ave to San Marcos Blvd 68.7 68.5 - - -0.2
San Marcos Blvd to Discover St 69.7 70.0 69.7 66.8 -2.9 Craven Rd
Discovery St to Foxhall Dr 71.3 71.5 70.3 71.4 0.1
Echo Ln to Rush Dr 71.3 71.5 70.3 71.4 0.1
Rush Dr to Twin Oaks Valley Rd 71.6 72.4 70.3 70.4 -1.2 East of Twin Oaks Valley Rd - - 69.3 67.0 -2.3
Rush Dr
Craven Rd to Discovery St 68.2 70.9 62.0 58.9 -9.3
1Where Year 2035 traffic numbers are not available for comparison, Year 2030 without project was compared to Year 2030 with Project scenario.
Sophia Habl Mitchell
Sophia Mitchell & Associates
P.O. Box 1700
Gualala, CA 95445
42428 Chisolm Trail
Murrieta CA 92562
phone 760-473-1253
5/13/22 21-90 UDSP Noise Letter
9 Table 4 (Cont.): Approved UDSP vs. Proposed UDSPA Related Noise Levels Roadway Segment
UDSP UDSP Amendment 2030 vs 2035 +
Project
(dBA Ldn)1 2030 2030 +
Project 2035 2035 +
Project
Twin Oaks Valley Rd
South of Village Dr 75.1 75.5 72.6 74.1 -0.9
Village Dr to Craven Rd 75.7 76.1 72.7 74.1 -1.5
South of Barham Dr 74.9 75.4 74.2 74.7 -0.3
Discovery St to Carmel St 76.3 76.2 73.4 73.4 -2.9
SR-78 WB Ramp to Civic Ctr Plaza Dwy 76.9 76.9 75.1 75.0 -1.9 Civic Ctr Plaza Dwy to San Marcos Blvd 75.4 75.5 74.4 74.5 -0.9 San Marcos Blvd to Richmar Ave 75.5 75.8 74.7 75.4 0.0
Richmar Ave to Borden Rd 73.9 74.6 73.1 73.8 -0.2
Barham Dr
Twin Oaks Valley Rd to Campus Wy 73.7 73.8 70.3 72.5 -1.2 Campus Wy to Industrial St 74.8 73.6 70.5 71.8 -3.0
La Moree Rd to Warplex Ave 74.3 74.5 70.6 70.8 -3.5
Warplex Ave to Woodland Pkwy 74.4 74.9 70.6 70.8 -3.6
East of SR-78 EB Ramp - - 70.6 70.8 -0.2
Las Posas Rd
SR-78 to Grand Ave 76.2 76.2 - - 0.0
Via Vera Cruz
Grand Ave to Linda Vista Dr 71.4 71.5 - - 0.1
Linda Vista Dr to San Marcos Blvd 70.7 70.9 - - 0.2
Grand Ave
Las Posas Rd to Via Vera Cruz 73.7 73.6 - - -0.1
Bia Vera Cruz to Bent Ave 71.9 71.8 - - -0.1
Bent Ave to San Marcos Blvd 70.5 70.5 - - 0.0
San Marcos Blvd to Discovery St 72.8 72.8 - - 0.0
Knoll Rd
Mission Rd to Los Vallecitos Blvd 70.7 71.7 - - 1.0
Los Vallecitos Blvd to San Marcos Blvd 71.5 71.3 - - -0.2 Westlake Dr
North of San Marcos Blvd 64.7 69.4 - - 1.8
South of San Marcos Blvd - 73.8 - - -
Pico Ave
Mission Rd to San Marcos Blvd 69.3 69.2 - - -0.1
1Where Year 2035 traffic numbers are not available for comparison, Year 2030 without project was compared to Year 2030 with Project scenario.
Sophia Habl Mitchell
Sophia Mitchell & Associates
P.O. Box 1700
Gualala, CA 95445
42428 Chisolm Trail
Murrieta CA 92562
phone 760-473-1253
5/13/22 21-90 UDSP Noise Letter
10 Conclusions
The proposed project will not create a direct impact of more than 3 dBA Ldn on any roadway segment for Year 2035 traffic volumes. Therefore, the proposed project’s direct contributions to off-site roadway noise increases will not cause any significant impacts to any existing or future noise sensitive land uses.
Sincerely,
Ldn Consulting, Inc.
Jeremy Louden, Principal