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City of Arden Hills <br />Project B2204011 <br />June 23, 2022 <br />Page 8 <br /> <br /> <br />importing clean, crushed rock that can be blended with the reclaimed material to improve the uniformity <br />of the resulting gradation prior to any direct reuse as an aggregate base. <br /> <br />C.1.c. Construction Disturbance <br />The clayey roadway subgrades will be sensitive to disturbance and strength loss if subjected to repeated <br />vehicle traffic. Subexcavation and recompaction or replacement of subgrade soils may be required if they <br />lose strength or become unstable as a result of construction activity or exposure to moisture. <br /> <br />C.2. Subgrade Preparation <br /> <br />C.2.a. Pavement Reclamation and Subgrade Preparation <br />For areas to be rehabilitated via FDR, we recommend the following steps for pavement subgrade <br />preparation, understanding the site will generally match existing grades. <br /> <br />1. Pre-mill where recommended, then reclaim the pavement as recommended in Section C.1.b <br />stockpile and/or redistribute excess reclaim material as necessary to construct the new <br />pavement sections. <br /> <br />2. Once the roadway sections are cut to grade, have a geotechnical representative observe the <br />excavated subgrade or top of reclaim material to evaluate if additional subgrade <br />improvements are necessary. <br /> <br />3. Scarify, moisture condition, and surface compact to at least 100 percent of standard Proctor <br />density for fine-grained soils or to the requirements of the MnDOT penetration index <br />method for granular soils. <br /> <br />4. Place pavement engineered fill to grade where required and compact in accordance with <br />Section C.2.b to bottom of pavement section. <br /> <br />5. Test roll the pavement subgrade as described in Section C.2.c. <br /> <br />C.2.b. Engineered Fill Materials and Compaction <br />If imported material is to be used, Table 4 contains our recommendations for engineered fill. Note that <br />similar materials compared to existing should be used to the degree possible; importing different soils for <br />backfill may create lenses that could trap water and result in differential frost heave and other <br />performance issues. If longitudinal transitions in soil type are required, we recommend tapering them at