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North Oaks Company LLC <br />Project B2402335 <br />August 22, 2024 <br />Page 18 <br />Even small amounts of frost -related differential movement at walkway joints or cracks can create <br />tripping hazards. Project planning can explore several subgrade improvement options to address this <br />condition. <br />One of the more conservative subgrade improvement options to mitigate potential heave is removing <br />any frost -susceptible soils present below the exterior slab areas down to a minimum depth of 4 feet <br />below subgrade elevations or to the bottom of adjacent footing grades. We recommend filling the <br />resulting excavation with non -frost -susceptible fill (i.e., clean sand). We also recommend sloping the <br />bottom of the excavation toward one or more collection points to remove any water entering the <br />engineered fill. This approach will not be effective in controlling frost heave without removing the water. <br />An important geometric aspect of the excavation and replacement approach described above is sloping <br />the banks of the excavations to create a more gradual transition between the unexcavated soils <br />considered frost susceptible and the engineered fill in the excavated area, which is not frost susceptible. <br />The slope allows attenuation of differential movement that may occur along the excavation boundary. <br />We recommend slopes that are 3H:1V, or flatter, along transitions between frost -susceptible and non - <br />frost -susceptible soils. Figure 3 shows an illustration summarizing some of the recommendations. <br />Figure 3. Frost Protection Geometry Illustration <br />PAVEMENT OR SLAB <br />FROST <br />DEPTH NON -FROST -SUSCEPTIBLE FILL <br />SLOPE TO DRAIN TILE <br />WHERE SUBGRADE <br />WOULD COLLECT WATER <br />\_t3H:1V SLOPE IN <br />FROST -SUSCEPTIBLE TRANSITIONS <br />MATERIALS <br />DRAIN TILE ROUTED TO SUITABLE <br />DISPOSAL SITE WHEN SUBGRADE <br />WOULD COLLECT WATER <br />Another option is to limit frost heave in critical areas, such as doorways and entrances, via frost -depth <br />footings or localized excavations with sloped transitions between frost -susceptible and non -frost - <br />susceptible soils, as described above. <br />4 :74 11, <br />INTEKTEC <br />