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17800 Newhope Street, Suite B, Fountain Valley, California 92708. Tel: (714) 751-3826, Fax: (714) 751-3928 <br />Earth Mechanics, Inc. <br />Geotechnical & Earthquake Engineering <br /> MEMORANDUM <br />EMI PROJECT NO: 12-109 <br />DATE: J a n u a r y 7 , 2 0 1 4 <br />PREPARED FOR: M r . B o B u r i c k / R B F C o n s u l t i n g ( R B F ) <br />PREPARED BY: ( R a j a ) S . P i r a t h i v i r a j a n d L i n o C heang / Earth Mechanics, Inc. (EMI) <br />SUBJECT: R e s p o n s e s t o C a l t r a n s R e v i e w C o m m e n t s <br />Preliminary Geotechnical Design Report (PGDR) and Structure <br />Preliminary Geotechnical Reports (SPGRs) for <br />Brea OH (Widen), Bridge No. 55-0482, 12-ORA-57, PM 20.61 and <br />Lambert Road UC (Widen), Bridge No. 55-0492, 12-ORA-57, PM 20.9 <br />12-ORA-57, PM 20.1/21.8 <br />SR-57/Lambert Road Interchange Improvement Project <br />Orange County, California <br /> EA 12-0C1100 <br />______________________________________________________________________________ <br />Earth Mechanics, Inc. (EMI) submitted the Preliminary Geotechnical Design Report (PGDR), <br />dated July 8, 2013, for the SR-57/Lambert Road Interchange Improvement project. EMI also <br />submitted the Structure Preliminary Geotechnical Reports (SPGRs) in the Advanced Planning <br />Study (APS) process for the widening of Brea Overhead (Bridge No. 55-0482) and Lambert <br />Road Undercrossing (Bridge N o , 5 5 - 0 4 9 2 ) , d a t e d A p r i l 3 0 , 2012. Caltrans Office of <br />Geotechnical Design South 1 (OGDS-1) has reviewed these reports and provided their comments <br />in a memorandum dated December 17, 2013. A copy of the Caltrans memorandum is provided in <br />Attachment 1. <br />This memorandum provides our responses to Caltrans OGDS-1 comments. For convenience, <br />Caltrans comments are provided in italics followed by EMI responses. <br />1.As mentioned in EMI’s SPGRs, the 1967 and 2008 as-built LOTBs for Brea Overhead (and <br />Lambert Road Undercrossing) conflict with regards to the soil type (cohesive vs. cohesionless). <br />Please provide future investigation plan (CPT etc.) to indicate whether Standard Penetration <br />Tests (SPT) or Modified California Samplers will be the more effective means of sampling. <br />Soil classification from the 2008 borings is supported by particle grain size analysis and <br />Atterberg Limit tests, whereas there is no laboratory soil test results included with the 1967 <br />LOTB sheet. Therefore, it is highly likely that the soil type in question is cohesive material as <br />indicated in the 2008 LOTB sheet. <br />As presented in SPGRs, we recommend drilling three soil borings for the widening of Brea OH <br />and two soil borings for the widening of Lambert Road UC. Location and depth of these soil