1318 37TH ST Geotech Report 2018-01-02 MF Import

i i T • James Pirie JN 97072 March 18, 1997 Page B All permanent cuts into native soil should be inclined no steeper than 2:1 (H:V). Fill slopes also should not be constr.�cted with an inclination greater than 2:1 (H:�. To reduce the potential for shallow sloughing, fill mus'. be compacted to the face of these siopes. This could be accompiished by overbuilding tl�e co��+pacte� fili and then trimming it back to its final incl:nation. Water should not be allowed to flow unconirollec: over the top of any temporarv or p�rmanent slope. Also, ali permanently exposed slopEs sho�ld be seeded with an appropria?e species of vegetation to reduce erosion and improve the stab�lity of the: surficial layer of soil. Drainaqe Considerations We recommend the use of footing drains at the base of footings, �vhere (1) crawi spaces or basements will be below a structure, (2) a slab is below the outside grade, or (3) the outside grade does not slope downward from a building. Drains should also be placed at the base of ell backfilled, earth-retaining walis. These drains should be surrounded by at least 6 inches of 1-inch- minus, washed rock and then wrapped in non-woven, geotextile filter fabric (Mirafi 140N, Supac �4NP, or similar material). At its highest point, a perforated pipe invert snould be at least as low as the bottorti of the footing, and it should be sloped for drainage. Drainage should also be provided inside the footprint of a structure, where (1) a crawl space �vill slope or be lower than the � surrounding ground surface, (2) an excavation encounters significant seepage, or (3) an excavation for a building will oe close to the expected high groundwater elevations. We can provide � recommendations for interior drains, should they become necessary, during excavation and � foundation construction. Alf roof and surface water drains must be kept separate from the foundation drain system. A typical drain detail is attached to this report as Plate 7. For ihe best long-term performance, perforated PVC pipe is recommended for all subsurface drains. No groundwater was observed during our field work. If seepage is encountered in an excavation, it should be drained from the site by directing it through drainage ditches, perforaled pipe, or French drains, or by pumping it from sumps interconnected by shallow conriector trenches at the bottom of the excavation. TFie excavation and site should be graded so that surface water is directed off the site and away from the tops of slopes. Water should not be all�wed to stand in any area where foundations, j slabs, or pavements are to be constructed. Final site grading in areas adjacent to buildings should ' slope away at least 2 percent, except where the area is paved. Water from roof, storm water, and j foundation drains should not be discharged onto slopes; it should be tightlined to a suitaole outfall ilocated away from any slopes. �I I ;' Pavement Areas ' All pavement sections may be supported on competent, nati�e soil or structural fill, provided these soils are in a stable, nor-yielding condition at the time of paving. Structural fill or fabric may be ded to stabilize soft wet or uns ble ar s. re us' ured nee , , ta ea We commend ing Supac 5NP, manufact by Phillips Petroleum Company, or a non-woven fabric ;�ith equivalent strength and permeability charac!eristics. In most instances where unstable subgrade conditions are encountered, 12 ir�ches . of granular, structural fill will stabilize the subgrade, except for very soft areas where additional fili GEOT[CH CONSULiANTS,INC. �I�� w -