Agenda - Council - 10/09/2018 - Laserfiche WebLink

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City of Ramsey Project B1705491 August 11, 2017 Page 8 We recommend thorough quality control practices, including frequent sieve analyses of the reclaimed material, if the product will be reused directly on site as aggregate base or as a stabilizing material with minimal processing. C.2.b. Pavement Subgrades The pavement subgrades will consist almost exclusively of sandy materials, though areas of clayey sand or lean and fat clay were also present. We anticipate the subgrade soils present beneath the streets will generally be suitable for pavement support in their current condition or with minor rework such as surface compaction. The exception is the swamp -deposited soils, which should be removed from excavations for pavements and in utility trenches. The shallow clayey sand or lean clay fill, present in ST-05, ST-C14 and ST-C15, may be wet or become wet upon exposure. These soils in particular may require additional work, such as drying or moisture conditioning, before they can be properly compacted. C.2.c. Utility Support and Impact of Groundwater The reuse of the utility trench backfill soils will have potential impacts on the pavement subgrades. If the backfill is not properly compacted, there is the potential for subgrade instability and settlement (and premature deterioration) of the driving surface. We anticipate the trench soils will consist mostly of granular soils (poorly graded sand and poorly graded sand with silt). In some cases, poor or unsuitable soils will be encountered that should be removed or will need additional effort to properly compact. Depending on the conditions at the time of excavation, drying of the clayey and silty soils may be necessary to achieve the levels of compaction recommended for utility support. Clayey and particularly silt -rich trench soils that are exposed to moisture will be more susceptible to strength loss and may also become unstable, which will require moisture conditioning or removal and replacement with suitable soils. Fat clay and organic soils (ST-C6, ST-C11) should not be used as utility support or backfill material. Groundwater was present in a limited number of borings (see Table 3), which may affect the placement of storm sewer. A coarse stabilizing aggregate could help with utility placement in wet or saturated conditions in these soils. BRAUN INIERItC