5.1. SR 01-17-2006 - Laserfiche WebLink

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KKE ARCHITECTS: 0606.1159.01 SITE FEASIBILITY STUDY REPORT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F~ SITE FEASIBILITY STUDY GREAT RIVER REGIONAL LIBRARY SYSTEM CITY OF ELK RIVER o Groundwater: Free groundwater was observed at all borings at depths of 12.5 to 14.7 feet below the ground surface, corresponding to elevations 866.3 to 869.8 feet. The average water level in the adjacent Lake Orono, "controlled by the power plant dam at the east end is 872 feet". STS interpreted from their data that there is a north/south groundwater level gradient, in addition to the usual downstream gradients along the flow lines of the two rivers. The groundwater level at the City Hall is closely related to the prevailing water levels in the Elk River and Mississippi River and ''will fluctuate as the river levels vary." o Flooding: There is a U.S. Corps of Engineering gauging station at the north end of the Parrish Avenue (County Road 42) bridge across the Mississippi River. STS was informed by the Corps of Engineers that the "1 DO-year flood elevation at the gauging station is about 866 feet and is 877 feet in Orono Lake." o Site Option C: The subsurface exploration identified above provides some insights into the general soil conditions of the adjacent properties but cannot be conclusive. o Report: The STS Consultants report is useful to project but not define foundation types allowable soil bearing pressures, lateral earth pressures on underground walls, pavement design, and other geotechnical related design and construction considerations. o Soils Assumption: There is likely to be more fill and grading disturbances but conditions should generally be similar to native sands. Because of the proximity to the City Hall site, assume most of the site will be covered with organic topsoil over natural sands that are loose at the surface and more compacted (medium) at lower levels. o Groundwater: Free groundwater was observed at borings at the adjacent City Hall site at depths of 12.5 to 14.7 feet below the ground surface, corresponding to elevations 866.3 to 869.8 feet. The average water level in the adjacent Lake Orono, "controlled by the power plant dam at the east end is 872 feet". Previous observations by STS interpreted from their data that there is a north/south groundwater level gradient, in addition to the usual downstream gradients along the flow lines of the two rivers. o Flooding: There is a U.S. Corps of Engineering gauging station at the north end of the Parrish Avenue (County Road 42) bridge across the Mississippi River. STS was informed by the Corps of Engineers that the "1 DO-year flood elevation at the gauging station is about 866 feet and is 877 feet in Orono Lake." These observations will apply to this site as well. GEOLOGICAL SUMMARY Preliminary geotechnical evaluations for the proposed sites will need to be conducted. Assume soils in all locations are not uniform in graduation or density. Assume there may be previous structures and other disturbances. Assume after corrections conventional spread-footing foundations may be used at all sites. Assume all building pads will be oversized. Pavement designs should not be exceptional but will need to be based upon the recommendations of a final geotechnical consultant. - 27-