Appendix E - Geology and Soils Geotechnical Supporting Information COMBINED

LESTER-SHRINER PROPERTY 132-8-2 Page 2 remnant barn structure that has fallen down. We understand that a residential development is currently planned for the site. The preliminary land plan prepared by RJA dated June 13, 2019, indicates the planned development will include up to 30 single-family homes. Appurtenant streets, utilities, landscaping and other improvements necessary for site development are also likely planned. We assume residential structures will be of wood-frame construction with concrete mat foundations. The land plan indicates grading will consist of cuts and fills up to about 25 to 30 feet deep. The primary site entrance will be near the west end of the site off of Dublin Canyon Road. We understand that two residential lots (Lots 29 and 30) will be located on the east side of Devaney Creek that will have a separate entrance from Dublin Canyon Road. 1.2 SCOPE OF SERVICES Our scope of services was presented in our proposals dated March 14, 2014, August 19, 2014, September 22, 2014 and February 26, 2020, and consisted of reviewing available subsurface soil data, reviewing available published geologic and seismic hazard maps of the area, a site geologic reconnaissance, supplemental exploratory test pits and borings, preliminary engineering analysis to evaluate grading, building foundations and pavements, and preparation of this preliminary report. A brief description of the prior and recent site exploration is presented below. 1.3 PREVIOUS EXPLORATION PROGRAM A preliminary field exploration was performed in 1997 by Lowney Associates that consisted of 19 exploratory test pits (TP-1 to TP-19) excavated to depths ranging from approximately 3 to 18 feet. Thirteen of the 19 test pits were located within the currently proposed development area (Lester parcel). The previous investigation also included performing four seismic refraction survey lines ranging from about 165 to 220 feet long. Only one of the refraction survey lines (L1) was within the currently proposed development area. The approximate locations of the previous test pits and seismic refraction survey lines are shown on the Site Topographic & Preliminary Geologic Map, Figure 2. Logs of the previous test pits are included in Appendix A. 1.4 RECENT EXPLORATION PROGRAM A supplemental field exploration was performed on the Shriner parcel that consisted of eight exploratory test pits (TP-1 to TP-8) excavated on August 30, 2014, to depths ranging from approximately 5 to 15 feet. Two supplemental borings were also performed on the western end of the Shriner parcel on October 7, 2014, to depths ranging from approximately 25 to 31 feet. Practical refusal was encountered in Boring EB-1 at a depth of 31 feet due to very hard bedrock. The test pits were excavated with four-wheel drive, rubber-tired backhoe equipment; the borings were drilled with track-mounted hollow stem auger drilling equipment that was equipped with a 5-foot-long dry-core sampling device. Ii! CORNERSTONE EARTH GROUP