Laserfiche WebLink
MainPlace Mall Transformation Project 12126.001 <br />liquefiable zone (Figure 5), it is our opinion that liquefaction could extend <br />northward beyond Boring LB-1. <br />3.4 Seismically -Induced Settlement <br />Seismically -induced settlement occurs primarily due to loss of strength or <br />stiffness in soils during and shortly after prolonged earthquake events. <br />We conducted seismically -induced settlement analysis using the soil profile and <br />sampling blow count data collected from Borings LB-1, LB-2, LB-4, and LB-7 <br />using computer software LiquefyPro. The calculations indicated that seismically - <br />induced settlement on an order of % to 1'/4 could occur in the vicinity of boring <br />LB-1, LB-4, and LB-7. The result is consistent with results of our exploration for <br />a project east of the site (Leighton 2004). However, settlement on an order of 3 <br />inches was calculated at boring LB-2 primarily due to moderately dense soils <br />exist at depths between 30 feet and 40 feet. Based on our observation during <br />field exploration and also review of the boring logs from previous investigations, <br />localized loose to moderately dense granular soils susceptible to seismically - <br />induced settlement could exist elsewhere at the site. Calculations of seismically - <br />induced settlement are also included in Appendix F, Liquefaction and <br />Seismically -Induced Settlement Analysis. <br />3.6 Seismically -Induced Lateral Spread <br />Soil liquefaction can result in lateral spreading or flow failure in sloping ground. <br />Since the site is slightly sloped, the potential for lateral spread to occur at the site <br />may exist within the liquefiable zone in the southern portion of the site as shown <br />on Figure 5. <br />3.6 Flood hazards <br />According to the City of Santa Ana's General Plan, Public Safety Element (City of <br />Santa Ana, 1982), the project site is located within an area with a 500 year flood <br />risk. This is based on the long history of the Santa Ana River overflowing its <br />banks and flooding the surrounding areas. To reduce this risk, the U.S. Army <br />Corps of Engineers (Corps) is constructing the Santa Ana River Mainstream <br />Project, which includes raising the height of Prado Dam and constructing new <br />gate -works to control water releases and other channel improvements. <br />Ito <br />9 I <br />Leighton <br />