729 100TH ST SE Geotech Report 2018-01-02 MF Import

. , ,,,�VIC' ' NELSON AND ASSOCIATES, INC. � � Consulung Engineering Gtology Apr11 7, 1989 Pro�ect No. 3989 Page 8 � Filter Gravel Backfill for Drains � Siev; Size � Passing by Weight �I 1 1/2" 100 3/4" 10 - 90 • 1/4" 30 - 60 No. 8 20 - 50 No. 30 0 - 30 No. 50 3 - 12 No. 200 0 - 1.2 The dralnage blanket should extend to within about two (2) feet of finished exterior grade and have a minimum thickness of 12 inches. The remaining two feet should be backfiiled with low permeability on-site sotls. The drainage blanket should be underlain by e perforated draln tile along the base of the wall . The t11e shovld be set such that a positive drainage gradtent is esteblished and access to en outlet provided. The use of ADS flexible type drain pipe is not recommended for greater than 4 foot embedment depths and/or where excavation and replacement type maintenance is not desired. Drainage Roofs and pavements will reduce the surface area available for natural inflltration withln the lot. This will in turn increase surface runoff. We recommend that roof drains, catch basins or other devices used to collect surface runoff be directed by tight line into the storm drain or other suitable system. Runoff should not be a1lowed to discharge onto sloping ground or to saturate foundatlon areas. Surface drains should be malntained separetely, and not interconnected with foundation or wali dralns. � Sldewalk Support Rockery � Me understand that a 5ldewalk is planned to extend along the southern half of the eestern stde of the structure. P�oposed elevations woutd not allow for a fill slope that could be tontatned within the property 1!ne. Therefore, a � rockery could be constructed elong this area ta protect the structural fill end sidewalk area from erosTon. A graAed filter should be used behind the � rock facing to reduce the potential for washing of the fi11 through the voids in the rockery face. Some repair and maintenance of the rockery/sidewalk area �