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HomeMy WebLinkAbout20200717111608344 (2)E t S. E. Medall & Associates, Inc. Consultants in the Earth Sciences 3030 South Bundy Drive, Los Angeles, California 90066 • 213/390.4079 2168 South Hathaway Street, Santa Ana, California 92705. 714/546.6602 December 22, W. 0. 605D Santa Ana County of Los Angeles Department of County- Engineer Engineering Geology Section 550 S. Vermont Los Angeles, California Attention: Mr. Ray Walbaum Subject: Periodic Grading Progress Report, Tr cts 29053, 34160 and 34161; for. the Period Novem er 7 through'December 18, 1978; Diamond Bar, unty of Los Angeles`, California. References: 1. Periodic Grading Progress- Report, Tracts 29053, 34160 and 34.161, for the period November 7 through December 18, 1978, Diamond Bar, County of Los Angeles, California.. 2. "Periodic Grading Progress Report, Tracts 29053 and 34160, Diamond Bar, County of Los Angeles, California"', by this firm 605D) dated August 14, 1978. m 3. Tract 290.53, 34161, "Reply to the County of Los Angeles- Geologic Review Sheets, dated February 1, 1978", dated March 24, 1978. 4. "Comments on Questions Raised by Mr. Dave Popplar. regarding Tracts 29053, 34160, 34161, Diamond Bar, County of Los Angeles, California", dated March.23, 1978. 5. "Addendum Comments Regarding Soil Engineering Report, dated February 20, 1978, Tracts 29053, 34160 and 34161, County of Los Angeles, California, dated March 23, 1978. 6. "Response to the Geology Appeal Board for the County of Los Angeles, Tracts 29053, 34160 and 34161, for the County of Los Angeles', dated March 20, 1978. County of Los Angeles Page 2 Gentlemen: December 22, 1978 W. O. 605D 7. "Supplemental Subsurface Exploration, Tracts 29053, 34160 and 34161,. Diamond Bar, County of Los Angeles, California", dated March 7, 1978. 8. "Response to Soil Engineering Section Review Sheet, dated February 6, 1978, Tracts 34160, 34161 (Parent Tract 29053), Diamond Bar Area, County of.Los Angeles", dated February 20, 1978. 9. "Supplemental Soils Engineering and Geologic Investigation and Grading Plan Review, Tracts 29053, 34161 and 34160", dated December 19, 1977. The following summarizes grading completed and geologic conditions encountered to date since our last ingrading progress report Reference No. 1) for Tracts 29053, 34160 and 34161, Diamond Bar, County of Los Angeles, California. Grading progress is presented in time intervals, with subheadings and commentary that summarize the grading work accomplished. NOVEMBER 7 2 0 BUTTRESS KEY The Buttress Key below Lots 79-96 (Tract 34161) has been inspected, mapped and approved by a geologist from this office. We believe key dimentions and location were constructed in accordance with the recommendations set forth in our previous report (Reference 9) for this project. S. E. Medall & ,associates, Inc. County of Los Angeles Page 3 FILL AREAS December 22, 1978 W. O. 605D Compacted fill is currently being placed in the area of the above mentioned Buttress Key. This buttress fill slope is estimated to be approximately 40 vertical feet below rough grade. Additionally, fill Lots 47-58 (Tract 34161) are believed to be within. 3 feet± of the rough pad grade. CUT AREAS Areas presently under excavation include Lots 1-7 and 60-92 (Tract 34161). These cut lots are believed to be within approximately 2 - 10 feet of rough grade. NOVEMBER 21 - DECEMBER 4 OVER -EXCAVATIONS Due to the presence of adversely oriented bedding planes, and/or i poorly cemented sandstones, exposed in rough cut excavations for slopes associated with Lots 65-75 (Tract 34161), the lots pads and f. p slopes have been over -excavated a minimum depth of 3 feet and re- > placed with compacted fill. These lots, as well as Lots 33-64 and 76 (Tract 34161), Lots 48-52 and 92-95 (Tract 34160) and Lots 49- 59 (Tract 29053),are believed to be within approximately 1 foot± of the rough pad grade. S. E. Medall & Associates, Inc. County of Los Angeles Page 4 CUT AREAS December 22, 1978 W. 0. 605D Areas currently under excavation include the above mentioned stabilization backcut as well as Lots 1-7, 17-32, 79-92 and 98-100 (Tract 34161). FILL AREAS Compacted fill materials are presently being placed in the buttress below Lots 79-99 (Tract 34161). This slope is believed to be with- in roughly 10=20 vertical feet of planned rough grade. DECEMBER 4 - 18 BUTTRESS KEY Excavation for the 61 foot high north -facing 1,:1 cutslope south of Lot 100 (Tract 34161), has exposed blocky to uncemented sandstone and locally adverse bedding conditions. Stability calculations per formed by this office for the slope indicated a.buttress fill was necessary for stability. The backcut and key have been inspected, e mapped and approved by the project field geologist and appear to have been constructed in accordance with our recent recommendations. To date, fill materials have not been placed within this key area. OVER -EXCAVATIONS Lots 22-25 (Tract 34161) have been over -excavated to a minimum 3 foot depth below pad grade and replaced with compacted fill materials to eliminate the influence of a sandstone-siltstone transition on S. E. Medall & Associates, Inc. County of Los Angeles Page 5 December 22, 1978 W. O. 605D structural foundations. To date, these lots, as well as Lots 26- 28 (Tract 34161), are believed to be within one foot± of rough grade. FILL AREAS Fill materials .are currently being placed in the areas of Lots 77- 93 (Tract 34161). These lots are believed to be within 1 foot± of pad grade. CUT AREAS Excavations for cut lots are presently confined to the area of Lots 7-17 (Tract 34161). The north -facing cut slope south of Lots 10-13 Tract 34161), to date have been cut to approximately pad grade. GEOLOGIC CONDITIONS With the exception of minor folding and some small shear zones, geologic conditions, including bedrock structure, are generally con- formable with the data presented in our previous reports (References 7 and 9 ) . CLOSURE If there are any questions concerning this letter please contact our office at your convenience. The findings contained herein are in accordance with generally accepted professional principles and S. E. Medall & Associates, Inc. County of Los Angeles Page 6 December 22, 1978 W. O. 605D practice in the fields of soil mechanics, foundation engineering and engineering geology. This warranty is in lieu of all other, warranties, either expressed or implied.. tfully subr4tted, Y WIL JIAOR. t1 i E.G. 866 Principal Engineering Geologist S. E. MEDALL & ASSOCIA KS, INC. c: (2) Addressee 1) Weatherfield Homes, Inc., Attention: Mr, Glen Bringle 1) VTN Consolidated JJB:WRM:pb S. E. Medall & Associates, Inc.