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Old Snelling Avenue Geotechnical Recommendations October 7, 2020 Page 3 soils. It is recommended to control potential surface water runoff that may occur due to precipitation or snow melt as this may impact construction and compaction of embankment soils. ROADWAY RECOMMENDATIONS Pavement Section Pavement design was performed for Old Snelling Avenue N. From Table 1, the average pavement section thickness is 24 inches with bituminous pavement under the aggregate base from borings B-1 through B-7. For Pavement design purposes, it was assumed that the proposed pavement section for Old Snelling Avenue would be comprised of bituminous pavement over aggregate base on existing fill rather than the existing bituminous pavement or aggregate base. It is understood that a full depth reclamation (FDR) of the existing pavement and base will be performed. The FDR will use the recycled material as a base for new bituminous pavement. It is recommended that the recycled material used as a base during the FDR be in accordance with Class 5 base for recycled materials (MnDOT 3138.2.E(2)). ESALs were estimated using traffic data from MnDOT. The traffic data and ESAL estimates are attached to this memorandum. R-value results from the geotechnical investigation were used as part of the pavement design. The R-value results are attached to this memorandum. The average R-value used in the pavement design was 36 with a standard deviation of 22. Pavement design was performed using MnPAVE-Flexible. The pavement design results are attached to this memorandum. Table 2 summarizes the recommended pavement sections. Table 2 – Recommended Pavement Section WATERMAIN RECOMMENDATIONS Watermain Pipe Backfill Watermain segments are proposed to be installed at a nominal depth of 7 to 8 feet below finished grade using and open cut trench. The trench is recommended to extend a minimum of 12 inches below the bottom of the pipe. Backfill around the pipe is recommended to conform to Select Granular Borrow (MnDOT 3149.2B.2). Place backfill in lifts of not more than 6 inches thick from the bottom of the trench to a minimum of 12 inches from the top of the pipe and compact to a minimum 95% of the Standard Proctor maximum dry density. Project specifications are recommended to include material testing provisions such as gradation and Standard Proctor tests for all sources of backfill. Trench Backfill Excavated trench material free of organics, deleterious debris, and contamination may be suitable for reuse as trench backfill. However, these materials may be wet and not suitable for immediate backfilling. The material may require spreading, disking, and/or other methods to dry it out in order to meet moisture requirements for acceptable compaction. Adequate space and time will be required at the project site to segregate unsuitable material from the soil and conduct material drying activities. If wet excavated material cannot be prepared for reuse as trench backfill, replacement backfill will be required. The replacement backfill is recommended to meet the criteria of Granular Borrow (MnDOT 3149.2B.1). Place trench backfill in loose lifts of 8 inches or less from 12 inches from the top of the pipe to the bottom of the aggregate base. Compact the trench backfill to a minimum 95% of the Standard Proctor maximum dry Roadway Aggregate Base (in.) Bituminous Pavement (in.) Old Snelling Avenue 8 4