March 20, Mr. Corey Juhl Juhl Energy Development Inc th Street SE Pipestone, MN 56164

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1 March 20, 2018 Mr. Corey Juhl Juhl Energy Development Inc th Street SE Pipestone, MN Re: Acoustic and Shadow Flicker Studies Davison County Wind, LLC Dear Corey: Tech Environmental, Inc. (TE) has completed sound and flicker modeling of the proposed 20 MW Davison County Wind Project in Beulah Township, South Dakota. These studies assumed nine GE wind turbines with an 80-meter hub height (T1 through T9). Project Sound Levels While there are no State or local regulations with decibel limits applicable to the Project, we recommend using a goal of 45 A-weighted decibels (dba) as a residential goal for non-participating (NP) residences, to prevent annoyance. Acoustic modeling was performed assuming the 9 wind turbines operating at maximum sound power, as measured by International Standard IEC , plus a 2- dba uncertainty factor. Acoustic predictions used the Cadna/A model, which conforms to International Standard ISO 9613, and simulates maximum sound levels. These calculations are conservative because these assumed weather conditions most favorable for sound propagation, namely a ground-based temperature inversion, along with winter ground conditions, and no attenuation from trees or other vegetation. Figure 1 displays the location of the 9 wind turbines plus 12 occupied dwellings. The 45 dba contour line is shown in Figure 1, which reveals that the 10 NP residences (R2, R3, R4, R6 through R12) are outside of the contour line, meaning predicted maximum sound levels at those non-participating dwellings are below 45 dba. A table providing the predicted sound levels for each residence follows Figure 1. All predicted sound levels at NP residences are within the proposed acoustic goal for Davison County Wind. 303 Wyman Street, Suite 295 Waltham, MA Phone: Web:

2 Davison County Wind March 20, 2018 Project Shadow Flicker There are no State or local shadow flicker limits. The guideline commonly used in our industry, to minimize flicker effects, is a limit of 30 hours per year at a non-participating residence. Flicker modeling was performed assuming operation of the 9 wind turbines and using the WindPro SHADOW model. Data regarding local average sunshine probability and turbine operation by wind direction were included in the calculations. These calculations are conservative because no adjustment was made for visual shielding by trees or other vegetation, and the rotor plane of the turbines was assumed to always be perpendicular to the line from the turbine to the sun, giving the largest shadow effect. Figure 2 displays the location of the nine wind turbines plus 12 occupied dwellings. The 30-hour per year contour line is shown in Figure 2, which reveals that the 10 NP residences (R2, R3, R4, R6 through R12) are outside of the contour line, meaning predicted shadow flicker at those non-participating dwellings are below 30 hours per hour. Shadow flicker is predicted to be zero hours per year at R12 north-northeast of the Project, and at R6 northeast of the Project. A table providing the predicted shadow flicker times per year for each residence follows Figure 2. All predicted flicker levels at NP residences are within the proposed flicker goal for Davison County Wind. Please call if you have any questions. Sincerely, TECH ENVIRONMENTAL, INC. Peter H. Guldberg, INCE, CCM Senior Consultant 4074/Letter Report March

3 ± R12 Legend Participating Residences Non-Participating Residences Turbines Sound Level 45 dba T1 T2 R6 R4 R7 R3 T3 T4 T5 T6 T7 T8 R9 R8 R2 T9 R1 R5 R11 R10 Figure 1 Maximum Sound Levels from the Davison County Wind Project Beulah Township, SD Miles

4 ± R12 Legend Participating Residences Non-Participating Residences Turbines Expected Shadow Flicker 30 hrs/year T1 T2 R6 R4 R7 R3 T3 T4 T5 T6 T7 T8 R9 R8 R2 T9 R1 R5 R11 R10 Figure 2 Expected Shadow Flicker Davison County Wind Project Beulah Township, SD Miles

5 Cadna Sound Modeling Results Davison County, SD Sound Height Coordinates Receptor ID Status Level X Y Z (dba) (m) (m) (m) (m) R1 P R2 NP R3 NP R4 NP R5 P R6 NP R7 NP R8 NP R9 NP

6 Expected Height Coordinates Receptor ID Status Shadow Flicker X Y Z (hrs:min/year) (m) (m) (m) (m) R1 P 33: , ,843, R2 NP 9: , ,843, R3 NP 5: , ,844, R4 NP 9: , ,844, R5 P 15: , ,843, R6 NP 0: , ,845, R7 NP 0: , ,844, R8 NP 1: , ,843, R9 NP 2: , ,843, R10 NP 0: , ,842, R11 NP 0: , ,842, R12 NP 0: , ,845,