11802 EVERGREEN WAY BASE FILE Geotech Report 2018-01-02 MF Import

�o��o�rono ta:'G/ q257478561 GEOTECH . � � PAGE 08 ' Lucia Development, LLC August18, 2005 JN 05233 Pege 7 should not be placed directly behind retaining walls due to their siit content. For increased protection, drainage composkes shouid be placed along cut slope faces, and the walls shouid be bac�lled entirely with free-draining soil. The later section entitled Oralnaqe Considerabons should also be reviewed for recommendations related to subsurface , drainage behind foundation and retafning walls. The purpose of these backfill requiremeMs is to ensure that the design cxiteria for a reta(ning wall are not exceeded because of a buiid-up af hydrostatic pressure behind the wali. Tha top 12 to 18 inches of the ba�il should consist of a compaded, relatively impermeable soii or topsoil, or the surtace should be paved. The ground surtace must also sfope away from backfilled 4�+!;; to reduce the potential !or surtace water to percolate Into the backfi0. The section entitled Ceneral �arthwork and Structura! Fill contains recommendations regarding the placement and compaction of structural fill behind retaining and foundatlon walls. The above recommendations are not intended to waterproof below-grade walls, or to prevent the fortnatlon of mold, mildew or fungi In intelior spacas. Over time, the pertortnance of subsurface drainage systems can dEgrade, subsurface groundwater flow pattems can change, and uti�ides qn break or develop leaks. There{ore, waterproo{�9 should be provided where future seepage through the walls is not acceptable. Thfs typically includes fimiting cold�oints and wall penetrations, and usfng bentonke panels or membranes on the outside of the walls. There are e variety of dffferent waterproofing materiats and systems;whlch should be installed by an experienced opntractor familiar with the anticipated construction and subsurface conditions, qpp�y�ng a thin coat of asphak emulsion to tha outside face of a wall is not consldered waterproofing, and will only help to reduce moisture genarated from water vapor or caplllary actian from seeping through the concrete. qs wP(h any project, adequate ventilation of basement and crawl space areas fs important to prevent a bulld up of water vapo� that Is commonly transmitted through concrete walls from the surroundin8 ��, even when seepage is not present This 15 appropriate even when waterproofing is appljed to the autside of foundation and retafning walls. We recommend that you co�tac� a specialty consultant ff detailed recommendations or speoifications related to watetproofing design, or minimiz(ng the potential for ir�festations of mold and mildew are desired. SLABS-ON-GRAD� � Due to poterttial differential settlement, we recommend that the buflding floors be sttucturally s�PParted on the deep foundation system, either through the use of a structural slab or a crawl space. Even where the exposed solls appear dry, water vapor will tend to naturally migrate upward through the soil to the new constructed space above ft. AII interior slabs-on-grade must be underlaln by a capillary break or drainage layer consisting of a minimum 41nch thlckness of gravel or crushed rock that has a fines content (percent passing the No. 200 sieve)of less than 3 percent and a sand content (percem passing the No. 4 sieve) of no more than 10 percent. As noted by ihe American Concrete Institute (ACI) In the Guides for Concrete Floor and Slab Structures, proper motsture protection is desirable immediatel�� below any on-grade slab that will be covered by tile, wood, rarpet, impertneable floor coverings, or any molsture-sensitive equipment or products. ACI also notes that vapor retarclers, such as 6-miI plasUc sheeting, are t�pically used, A vapor retarder is defiined as a material with a pertneance of less than 0.3 U5 pertns per square foot (ps� per hour, GEOTECH CONSULTANTS,INC.