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Proposed Senior Living Facility—Mounds View, Minnesota Kilo Project 25-2066—December 30,2025 Page 7 of 9 The soils types encountered on the site are bolded in the table above for reference. Based on the soil types observed in the recovered soil samples, the soils above the testing elevation have the suitable infiltration capacity for the construction of an infiltration stormwater feature, based on shallow feature depths. No groundwater was observed in the borings, but is anticipated near the wetland elevation of 908± feet MSL. No changes in soil colorization representative of seasonal high groundwater levels were observed above this depth. Given these observations, no "confining layer" due to high groundwater was present within the upper 6± feet of the soil profile. The design infiltration rate of 0.80 inches per hour for Sand or Sand with Silt should be used for the design infiltration rates for the stormwater management areas with a bottom of feature within of 3±feet of the existing site grades to maintain code-required separation above confining layers. In order to construct an infiltration stormwater feature, any soils that would be classified as organics, cobbles, boulders, silty sand, clayey sand, or sandy clay should be removed from the proposed stormwater feature area and used in other locations on site or disposed of offsite. Then, the upper 12 inches of the poorly graded sand subgrade should be scarified and left in an uncompacted state. The area should be protected from construction traffic after the scarification. The site should be graded to direct stormwater runoff to the at-grade feature or a storm sewer collection system may be appropriate. The feature should be protected to minimize erosion upstream of the feature and sediment deposition in the feature, which will negatively impact infiltration rates. This protection can be accomplished using velocity dissipators, rip-rap linings, or other means. Kilo understands the majority of the site will include stormwater collection systems discharging into the proposed stormwater system directly. Periodic maintenance to remove accumulated fines material from the base of the feature should be anticipated during the lifetime of the infiltration feature. It should be noted that the infiltration rates above may be used without site-specific infiltration testing, but higher rates may be feasible to achieve with on-site double-ring infiltration testing. The stormwater areas will require sizing and locating based on-site constraints. The only limiting factor on the bottom of feature elevation is maintaining a three-foot separation from the confining layer level, which is anticipated to be near 6±feet below existing site grades during the site testing. The depth of the feature will be limited by the 48-hour drawdown depth (38.4 inches, based on 0.80 in/hr infiltration). The storage volume of the feature will be dependent on the design storm calculations, new building and impervious areas, and the lateral extents of the feature. Determining this storage volume will depend on the project design storm required by the MPCA, which is typically either the 2- year, 5-year, or 10-year design storm. Determination of the required design storm was beyond the authorized scope of this report. It should be noted that the authorized scope of work did not include infiltration testing to determine infiltration rates above those specified in the Minnesota Stormwater Design Manual. The scope of services did not include HydroCAD modeling of the site to determine runoff volumes. This should be completed by others after the proposed site plan has been completed for impervious area calculations. Erosion Control Recommendations Two main methods are utilized to control erosion both during construction and during the operations phases of a project — velocity dissipation and surficial armoring. These methods can be utilized separately or in tandem and may require stabilization measures along multiple points along existing