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Taking these factors into consideration, there are 22 receptors within this analysis that exceed MPCA noise standards and merit noise wall consideration (Wall 1:R1 — R11, Wa112: R22, and Wa113:R27- R-28 and R30-R32C). It should be noted that R36-R38 are commercial properties and meet the FHWA criteria for developed land. Also, as stipulated in Minnesota Statute 116.07, Subd. 2a, Rice Street and County Rd. B are exempt from the state noise standards. The statute states: (2a) `No standards adopted by any state agency for limiting levels of noise in terms of sound pressure which may occur in the outdoor atmosphere shall apply to (1) segments of ti^unk highways consti^ucted with federal interstate substitution money, provided that all reasonably available mitigation measures are employed to abate noise, (2) an existing or newly constructed segment of a highway, provided that all reasonably available noise mitigation measures, as approved by the commissioners of the department of transportation and pollution control agency, are employed to abate noise, (3) exceptfor the cities ofMinneapolis and St. Paul, an existing or newly constructed segment of a road, street, or highway under the jurisdiction of a road authority of a town, statutory or home rule charter city, or county, exceptfor roadways for which full access has been acquired" These roadway improvements are only required to only meet the FHWA noise criteria outlined above in Table 2. 4.1 Noise Wall Modeling Three 20 foot noise walls (Mn/DOT ma�mum) and three 10 foot noise walls, were placed within the MINNOISE model separately to gauge effectiveness during "worst case" scenarios for both daytime and evening time periods (for detailed MINNOISE information for noise wall analysis, please refer to Appendix A/"MINNOISE Model Data"). These noise walls were analyzed between the homes and the roadway residing on: ■ the north side of Highway 36, west of Rice Street (Wall #1), ■ the north side of Highway 36 and the frontage road east of Rice Street (Wall #2), and the south side of Highway 36, west of Rice Street (Wall #3). Figure 1 in Appendix B shows the locations of the modeled noise walls. Multiple scenarios were run to optimize the length of the noise walls. Only the wall length scenarios that showed the most effective noise reduction are included. Table 6 illustrates the complete noise impact survey including Design Year 2033 levels without a noise barrier, Design Year 2033 with a noise barrier, and resulting noise level differences for the Daytime and Nighttime scenarios. Table 6 also illustrates the modeled noise reduction with 10 and 20 foot walls at each receptor used in the model. The applicable noise standard for each receptor is also included in Table 6 as well as the number of residences with at least a 5 dB reduction. 4.2 Cost-Effectiveness Analysis A cost-effectiveness analysis has been performed as part of the documentation for this project. For noise walls to be considered reasonable, the cost effectiveness shall not exceed $3,250 per decibel of reduction per residence. The cost effectiveness is calculated for individual barrier segments. For barriers to be warranted, they must be acoustically effective by providing a meaningful reduction in noise, defined as a five decibel reduction or more. The noise wall cost-effectiveness calculations are included in this report (Table 6). Noise walls might not be cost-effective for the following reasons: ■ Topography may create a situation where a noise wall cannot effectively block the line of sight from the roadway to the receptor. Noise Analysis RAMSP 105803 TH 36 and Rice Street Interchange Page 6