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�� Valata Road 5-Lot Reszdential Developxnent Decer$�B� - Page 129 <br /> � <br /> �� <br /> Up to S feet of creek bank depasits exist along the creek margins, overlying tl�e exp�.nsive clay <br /> soils. <br /> Groundwater <br /> Groundwater was encauntered during subsurface exploration at a depth of 20 feet below the <br /> existing g�ound surfaee. Historical water has been recorded to vary betwee� 10 and 20 feet ir�t�ie <br /> vici�ity of the site and was mEasured as high as 15 feet bgs by Terrasearcl�{1995) on thE acljacent <br /> property to the east but was typically at approximately 17 feet bgs. We do not anticipate <br /> ground�vater being an issue at the site. Elluviated soils encountered at approximate�y 18 feet bgs <br /> indicate that groundwater has been as high as 18 feefi at the site. <br /> Seismicity <br /> The San Francisco Bay area is recognized by gealogists and seismologists as one of t�e most <br /> seismically ac�ive regions irn the United States. The significant earthquakes in this area are <br /> generally as,sociated witl� crustai movement along r�rell-defined, ac�ti�re fault zones wl�icl� <br /> regionally trend in a northwesterly direction. Although research on earthc�uake prediction has <br /> g.reat�y increas�d in recent years, seismologists cannot predict when and where an earthquake wi11 <br /> occur. Nevertheless, on the basis of current technology, it is reasonable to assume tnat tne <br /> proposed �ight st�zctures will be subjected to at least one moderate to severe earthquake during <br /> their Iifetime. During such ar� eart�iquake, the danger from £aulfi offset on the site is low, but <br /> s�rong shalcing of the site is likely to occur azid, thexefore, the praj ect should be designed in <br /> accordance with the seismic design provisians o�the latest California Buzlding Code. It should <br /> be understood tYiat fhe Califo�..ia Building Code seismic design parameters are not intended to <br /> prevent structural damage duri�g an earthquake, but to reduce damage and rninimize loss of life. <br /> Li uefacfion <br /> It is our opinion t1�at liq�efaction related settZEment will have a minimal impact on the proposed <br /> subdivision. If liquefaction should occur, deep-seated settlement on the order of 1 inch could <br /> possibly occur. The likelihood of sur#�ace manifestation due to liquefaction of deep-seated loss af <br /> cohesion at the site is considered low. <br /> 4 <br />