Agenda - Council - 10/26/2021 - Laserfiche WebLink

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Groundwater Ground water was encountered in one of the sol borings (SB-02) at about 12 feet below the ground surface. With pipe inverts anticipated to bear about 7 to 10 feet below the ground surface we do not anticipate that groundwater will be encountered during spot utility repairs and do not anticipate that dewatering will be required. 4.3 Utility Recommendations Spot utility repairs could be included in this project. We anticipate that the existing utilities bear at depths ranging from about 5 to 10 feet below the ground surface and at these depths the pipes likely bear on sandy alluvial soils or compacted engineered fill which in our opinion are suitable for pipe support. We recommend removing all vegetation, topsoil, organic soils and any soft or otherwise unsuitable soils, if any, beneath utilities prior to repair or placement. We assume that open cut excavation techniques will be used for pipe installation. We further assume that typical excavations depths will be on the order of 5 to 10 feet below the ground surface. At typical 1:1 excavation backslopes, the excavation will extend about 5 to 10 feet beyond the edges of the excavation. The excavation may extend into/ onto adjacent properties posing a risk of undermining structures on those properties. In addition, the soils could slough as they are excavated resulting in side slopes flatter than 1:1 further increasing the horizontal limits of the excavation. If site constraints will limit the excavation, trench boxes or temporary shoring may be required. Backfilling New pavements will be constructed over the top of the utility trench(s) and the soil excavated for pipe installation will likely be placed back in the excavations, to the greatest extent possible. As noted above, the soils encountered in the borings in our opinion is suitable for reuse. We recommend that any buried topsoil, organic soils and any soft or otherwise unsuitable materials, if encountered, be removed and replaced with suitable compacted engineered fill. We recommend bedding material be thoroughly compacted around the pipes. We recommend trench backfill above the pipes be compacted to a minimum of 95 percent beneath pavements, the exception being within 3 feet of the proposed pavement subgrade, where 100 percent of standard Proctor density is recommended. In landscaped areas, if any, we recommend a minimum compaction of 90 percent. 4.4 Pavement Recommendations The City of Ramsey may have standard plates that dictate bituminous pavement design. If so, we assume the pavements be designed in accordance with the appropriate standard plates. The following paragraphs provide general pavement recommendations in the absence of standard plates. Reconstruction In areas that will be reconstructed we recommend removing all vegetation and topsoil, if any, and all pavements, aggregate base, organic soils and any soft or otherwise unsuitable materials from beneath the pavement subgrade. Prior to placing the aggregate base (Class 5) we recommend compacting the subgrade soils to provide a more uniform surface and to identify soft, weak, loose or unstable areas that may require additional subcuts. Backfill, if needed, to attain pavement subgrade elevation can consist of any mineral soil provided it is free of organic material or other deleterious materials. However, we recommend additional fill, if needed, consist of sandy soils similar to the on -site materials. 7