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rKLE NFELOER <br /> Bright People.Righ}So7utFons. <br /> Consideration could be given to the use of cementitious slurry mixtures such as lean concrete, <br /> Controlled Low Strength Material (CLSM) or Controlled Density Fill (CDF) for bedding and initial <br /> backfill around the pipes. In general, we recommend cementitious slurry mixtures have a 28-day <br /> compressive strength between 50 and 200 psi. <br /> 5.2.11 Filter Fabric Envelope <br /> To reduce the potential for migration of the trench backfill soil into the voids in crushed rock <br /> bedding and initial backfill, a non-woven filter fabric should be placed between backfill soils and <br /> the underlying crushed rock. Filter fabric should be laid-out and overlapped according to the <br /> manufacturer's recommendations. Recommended minimum filter fabric specifications are <br /> presented in Table 5-2. <br /> Table 5-2 <br /> Recommended Filter Fabric Specifications <br /> Property Requirement Test Method <br /> Apparent Opening Size AOS #70 U.S. Standard Sieve Size ASTM D4751 <br /> Grab Tensile/Elongation 120 lbs./50% ASTM D4632 <br /> Puncture Strength 70 Ib. Minimum, Average Roll Value ASTM D4833 <br /> Geotextiles such as Mirafi 140N and similar products should meet the above specifications. <br /> 5.3 2019 CBC SEISMIC DESIGN PARAMETERS <br /> For a 2019 California Building Code (CBC) based design, the estimated Maximum Considered <br /> Earthquake (MCE) mapped spectral accelerations for 0.2 second and 1 second periods (Ss and <br /> Sj), associated soil amplification factor (Fa), and mapped peak ground acceleration (PGA) are <br /> presented in Table 5-3. Corresponding site modified (SMs) and design (SDs) spectral <br /> accelerations, PGA modification coefficient (FPGA), PGAM, risk coefficients (CRs and CRS), and <br /> long-period transition period (TL) are also presented in Table 5-3. Presented values were <br /> estimated using Section 1613.3 of the 2019 California Building Code (CBC), chapters 11 and 22 <br /> of ASCE 7-16, and the Structural Engineers Association of California (SEAOC) and California <br /> Office of Statewide Health Planning and Development (OSHPD) U.S. seismic design maps2. <br /> 2 https://seismicmaps.org/ <br /> 20210067.001 A/ST020R111447 Page 16 of 37 May 11, 2020 <br /> ©2020 Kleinfelder www.kleinfelder.com <br />