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*:/ : 11-1 h WA <br />requirements in the restroom and shade structure construction. Seismic ground shaking impacts would be <br />less than significant, and no mitigation measures are required. <br />iii) Seismic -related ground failure, including liquefaction? <br />Less Than Significant Impact. Liquefaction occurs when loose, water -saturated sediments lose strength <br />and fail during strong ground shaking. Liquefaction is defined as the transformation of granular material <br />from a solid state into a liquefied state as a consequence of increased porewaterpressure. Both sandy and <br />clayey soils are susceptible to loss of strength and stiffness. Based on the State of California Seismic Hazard <br />Zones map for the Tustin Quadrangle and Newport Beach (CGS 2001, CGS 1998), The 6th Street Site is <br />not in an area that has been identified as potentially susceptible to liquefaction, and the Raitt Street Site is <br />identified as within the liquefaction zone. However, based on the type of development proposed at the <br />site, such as underground utilities, playground equipment, restroom, and shade canopies, impacts from <br />liquefaction are not expected to expose substantial number of people of structure to safety impacts related <br />to liquefaction. Additionally, the proposed project would be required to adhere to existing building and <br />grading codes. Compliance with the CBC and city's grading codes contain provisions for soil preparation <br />to minimize hazards from liquefaction, therefore, a less than significant impact is anticipated Impacts <br />would be less than significant, and no mitigation measures are required. <br />iv) Landslides? <br />No Impact. Landslides tend to occur in weak soil and rock on sloping terrain. The landslide hazard zone <br />generally indicate steep hillslopes composed of weak materials that may fail when shaken by an earthquake <br />(DOC 2018). The replacement park sites have been previously developed and are relatively flat without <br />noticeable slopes of elevation differences. Based on the State of California Seismic Hazard Zones Map for <br />the Tustin and Newport Beach Quadrangles (CGS 2001, CGS 1998), both replacement park sites are not <br />in an area that has been identified as potentially susceptible to seismically induced landslides. No impact <br />would occur, and no mitigation measures are required. <br />b) Result in substantial soil erosion or the loss of topsoil? <br />Less Than Significant Impact. Erosion is a normal and inevitable geologic process whereby earthen materials <br />are loosened, worn away, decomposed, of dissolved, and removed from one place and transported to another. <br />Precipitation, water, waves, and wind are all agents of erosion. Ordinarily, erosion proceeds so slowly as to be <br />imperceptible, but when the natrual equilibrium of the environment is changed, the fate of erosion can be <br />greatly accelerated. This can create aesthetic and engineering pfoblems. Accelerated erosion within an urban <br />area can cause damage by undermining structures, blocking storm sewers, and depositing silt, sand, of mud in <br />toads and tunnels. Eroded materials are eventually deposited into coastal and local waters where the carried silt <br />remains suspended in the water for some time, constituting a pollutant and altering the normal balance of plant <br />and animal life. <br />The replacement park sites are currently vacant with bare soils, therefore, resulting in some erosion impacts. <br />Additional erosion would occur during grading and construction activities temporarily, as soils are disturbed <br />and moved around However, long-term erosion and loss of topsoil would be less, since the majority of the <br />75C-90 <br />