820 WAVERLY AVE 2018-01-02 MF Import

� � � . � Harris•Tsang Architects E-4Z12 December 30, 1988 PaQe 6 � i � � lf seepagc is encountered in foundation excavations during construction, we recommend your � contractor slope the bottom of the excavation to a�e or more shallow sump piu. 9be � ` collected water can then be pumped from these piu to a positive and permanent discharge, � such as a nearby storm drain. Depending on the magnitude of such seepage, it may also be f necessary to interconnect the sump pits by a system of shallow mnnector trenches. ` We recommend you install footing drains around the building perimeter. These drains � should consist of a four-inch minimum diameter perforated or slotted rigid drain pipe laid at, or just below, the bottom of the footing with a gradient sufficient to mitiate flow. The drain line should be bedded on, sunounded by, and covered with a free-draining crushed ( rock or other free-draining granular material. Once the drains are installed, with the exception o► the upper twelve (12) inches, the excavation can be backfilled with a granular fill materiai. � The su�cial twelve (12) inches � of fill should rnnsist of compacted and relatively impermFable soil. It can be separated from the vnderlying more granular drainage material by a layer of building paper or visqueen. The surface should be sloped to drain away from the building wall. Alternatively, the surface can be sealed with asphalt or concrete paving. A typ�cal detail is provided on � Plate 8. Roof dowmspouts and perimeter drains must be separately tightlined to discharge. We recommend you install sufficient cleanouu at strategic locations to allow for periodic maintenance of the footing drain and downspout tightline systems. ' We recommend the appropriate locations of subsurface drains, if needed, be established during grading operations by ECI's representative at which time the seepage areas, if present, may be more clearly defined. Pa��ement Areas We recommend the subgrade be treated and prepared as described ia the Site Preparation section of this report. This means at least the top twelve (12) inches of the subgrade should be compacted to 95 percent of the maximum dry densiry (per ASTM D-1557-78). It is possible that some localized areas of soft, wet or unstable subgrade may still e�cist after this process. If so, they may require overexcavation of the unsuitable materials and their replacement with a compacted structural fill or a crushed rock. Depending on the nature � of the prepared subgrade at the time of construction, it may also be necessary to use a geotechnical fabric to separate pa�•^ment materials from the underlying subgrade and to help strengthen the pavement section. Eerth Consultants, Inc. I