02-27-2002 Council Agenda - Laserfiche WebLink

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Mr. Sam Roberto Project B B XX -01 -1 1 9A May 24, 2001 Page 4 compacted. These things considered, consideration should be given to: (I) removing and replacing both the existing fill and the peat with compacted backfill, (2) removing the existing fill and peat to allow the proposed residence to be supported on the underlying alluvial and glacial soils down approximately 10 feet, or (3) supporting the residence on piles driven through the existing fill and peat, and into the underlying alluvial soils and glacial soils. Given the depth of the existing fill and peat, it is our opinion that the most economical of the three options provided above is to remove the existing fill and peat, and replace it with compacted backfill. While it may be possible to incorporate a basement level into the proposed residence and thereby limit the volume of replacement backfill required, the shallow groundwater encountered will not likely allow a full basement to be constructed. While the glacial soils present below the existing fill and peat appear capable of supporting replacement backfill and the assumed building loads, the alluvial soils do not. Based on the penetration resistance values recorded, we expect that alluvial soils exposed in excavations to remove the existing fill and peat will be waterbearing and unstable. While it may be possible to establish a stable platform atop the alluvial soils with a thick lift of coarse, free - draining sand, it may ultimately be necessary to remove some or all of the alluvial soils (down to glacial soils) to facilitate the placement and compaction of backfill. C.4. Reusing On -Site 1Vlaterials The swamp- deposited peat will not be suitable for reuse, and will have to be hauled from the site unless there are landscaping applications for it. Portions of the existing fill may be suitable for reuse, provided they are free of debris and organic material. Alluvial and glacial soils will initially be difficult to reuse because they will be wet. While it may be possible to spread and dry these soils prior to reusing them, it may be economically more practical to just haul them off site and replace them with drier, imported soils.