CCP 02-19-2002 - Laserfiche WebLink

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Gatewav Business Center - Arden Hills, MN EAW September 2001 . Approximate depth (in feel) to bedrock: Boring depths ncver reached bedrock, 200 feet, according to the Ramsey County Geological Atlas Minimum: Average: 200 A preliminary Geoteehnical Exploration and Review, November 22, 2000, a Phase I Environmental Assessment, January 4, 2001, and a Phase IT Environmental Assessment, May 3, 2001 (all available upon request) were prepared for the site, See appendices for excerpts from these reports. The Phase I and IT EAs did not investigate conditions on the A TS Steel property. According to the soil boring report, groundwater levels are not easy to determine, due to the relatively slow-draining silty/clayey soils, which can cause perched water to develop, Piezometers and long- term monitoring are necessary to better determine groundwater levels, Describe any of the following geologic site hazards to ground water and also identify them on the site map: sinkholes, shallow limestone formations or karst conditions, Describe measures to avoid or minimize environmental problems due to any of these hazards, . The Phase I Environmental Assessment states that, according to the Ramsey County Geologieal Atlas, the uppermost bedrock formation at the site consists of the Prairie du Chien Group. The upper part of the Prairie du Chien Group is thin-bedded, sandy or oolithic dolostone that may contain karst solution cavities, The lower part of the Prairie du Chien Group is massive or thick-bedded dolostone. . The Preliminary Geotechnical Exploration and Review, November 22, 2000 (Appendix H), provided the following recommendations for the proposed development: . The proposed offiee buildings can be supported on spread footing foundations designed for an allowable bearing pressure of 3,000 psf to 4,000 psf after soil correcti on. . The soil correction should inelude removing the surficial fill, topsoil, swamp deposits and softer (N ~ 5 bpf) clayey soils, . The floor slab ean be supported on grade after performing soil correction, . Alternatively, the proposed five-story office building ean be supported on a pile foundation, if foundations designed for a 4,000 psf bearing pressure are not practical. . Perimeter drain tile should be installed around below-grade building space. . Pavements can be supported on the non-organic site soils after surface compaction and placement of compacted fill to attain plan grade. Soils which become unstable during the surface compaction should be subcut and replaced with better quality material to attain grade. . Placement of a I-foot-thiek sand layer in the upper portion of the sub grade ean improve pavement performance, The pavement should be designed for an R-value of 10 if the site soils are utilized for subgrade. If a I-foot-thick sand layer is placed in the upper portion of the subgrade, the pavement can be designed for an R-value of 20, Page 19