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Home My WebLink About20200717111448906S. E. Medall & Associates, Inc. Consultants in the Earth Sciences 3030 South Bundy Drive, Los Angeles, California 9 2168 South Hathaway Street, Santa Ana, California 0066 • t4Yi3 b 92705 7141546-6602 November 7, 1978 W. O. 605D County of Los AngelesDepartmentofCountEngineerPYgi_;I1, Engineering Geology Section 550 S. Vermont Los Angeles, California Attention: Mr. Ray Walbaum Subject: Periodic Grading Progress Report, Tracts 29053, 34160 and 34161, for the Period Au ust 14 Thru November 6, 1978, Diamond Bar, County,_of Los Angeles, California. References: 1) "Periodic Grading Progress Report, Tracts 29053 and 34160, Diamond Bar, County of Los Angeles, California", by this firm (W.O. 605D) dated August 14, 1978. 2) Tract 29053, 34160 and 34161, "Reply to the County of Los Angeles Geologic Review Sheets, dated February 1, 1978", dated March 24, 1978. 3) "Comments on Questions Raised by Mr. Dave Popplar regarding Tracts 29053, 34160, 34161, Diamond Bar County of Los Angeles, California", dated March 23, 1978. 4) "Addendum Comments regarding Soil Engineering Report, dated February 20, 1978, Tracts 29053, 34160, and 34161, County of Los Angeles, California', dated March 231 1978. 5) "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. 6) "Supplemental Subsurface Exploration, Tracts 29053, 34160, and 34161, Diamond Bar, County of Los Angeles, California", dated March 7, 1978. County of Los Angeles Page 2 Gentlemen: November 7, 1978 W.-O. 605D 7) "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. 8) "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. AUGUST 14 - 28, AUGUST 28 - SEPTEMBER 11 Alluvial Removal Canyon clean -out operations have been completed, inspected, mapped and geotechnically approved in the canyons beneath the -- following lots: 1) Lots 1, 41, 60, 62, 68, 69, 89 and 97, Tract 29053. 2) Lots 64-66, 73-75, 87, Tract 29053. 3) Lots 9-11, Tract 34160. 4) Lots 8-11, Tract 29053. 5) Lots 54, and 61-65, Tract 34161. S. E. Medall & Associates, Inc. Shear Key The recommended shear key north of Lots 1-13, Tract 29053 was excavated into competent bedrock. This key excavation was 1800 feet long, and ranges from 15 to 25 feet wide. Additionally r a subdrain system was installed per plan at the bottom inside edge of the keyway. Landslide Removal Removal of landslide debris in the vicinity.of Lots 97-101, Tract 29053 is currently underway. A 15 foot back -cut along the south and west perphery of the slide has been mapped. Geologic mapping and inspection will continue as the removals descend. Buttress Keys . The following buttress keys have been excavated,inspected, mapped and approved: Location Width (Ft.) Depth (Ft.) Above Lots 39 & 40, Tract 34160 50 -5._ Above Lots 20-25, 28-29 Tract 34160 120, 7 Northeast of Lot 25 and Northwest of Lot 26 Tract 34160 60 5 Stabilization Fills The northwest --facing side -yard cut slopes associated with Lots 32-34, Tract 34160, have been stabilized in accordance with our recent S. E. Medall & Associates, Inc. County of Los Angeles Page 4 November 7, 1978 W. O. 605D recommendations. These lots as well as Lot 31 have been over -excavated and replaced with compacted fill to eliminate adversely oriented bedding plane within these slopes. Additionally the entire lot area and front yard slope of. Lot 25 has been over -excavated and replaced with compacted fill. Fill Areas Fill materials. are currently being placed in the area of Lots 10-13, 20-25, 38, 29, and 63-72, Tract 34160. The following fill lots of Tract 34160 are believed to be within one foot.± of finished grade:.Lots 1 & 2, 10-13, 26, 27, 30-34, 45-47 and 60-72. T - - - Areas currently under excavation are restricted primarily to the landslide removal as previously mentioned. SEPTEMBER 11-25, SEPTEMBER 25 - OCTOBER 9 Alluvial Removals The following alluvial canyon clean -outs have been completed: 1) Lots 28, 49, 56-59, Tract 29053 2) Lots 80, 81, Tract 34160 and Lot 46, Tract 34161. Additionally, alluvium in the area of Gold Run Drive and Lots 1 and 101, Tract 29053 has been removed to competent material. S. E. Medall & Associates, Inc. County of Los Angeles Page 5 November 7, 1978- W. O. 605D Subdrain systems have been installed as recommended in all canyon areas and inspected by a geologist from this office prior to fill placement. Shear Key The 15 foot deep shear key north of Lot 35, Tract 29053 has been excavated as planned. Dimensions were observed to be in accordance with our recommendations. Buttress Keys The following buttress keys, presented in tabulated form, have been excavated, inspected, mapped and approved: Location Width (Ft.) Depth (Ft.) Northeast of Lot 1 Tract 29053 Northeast of Lot 96 Tract 29053 East of Lot 95 Tract 29053 Northwest of Lot 95 Tract 29053 Above Lots 80-84 Tract 34160 Lots 43-46 Tract 29053 Below Lots 35-40 Tract 29053 15 3-9 15 3 20 .5 15 3 120 7 15 3 50 5 S. E. Medall & Associates, Inc. County of Los Angeles Page 6 November 7, 1978 W. O. 605D Fill Key A fill key measuring from 15 to 20 feet wide and from 3 to 5 feet deep has been constructed at the toe of an 18 foot high south facing 2:1 fill slope below Lots 1-5, Tract 34161. This key has been inspected, mapped and approved. Landslide Removal Removal of landslide debris has been accomplished in the area of Lots 97-101, Tract 29053. Competent undisturbed bedrock materials were observed at the bottom,of the excavation. Geologic structure has been mapped in the removal area and approved. Fill placement in this area has proceeded and is believed to be currently to within one foot ± of final pad grade. Fill Areas Presently compacted fill materials are being placed above the canyon area below Lots 68-83, Tract 29053, and Lots 41-47, Tract 29053. Fill lots believed to be within one foot ± of final pad grade are presented as follows: Lots 1-4, 9-19, 94-101; Tract 29053 and Lots 20-25, 73-91, 53-59, Tract 34160. S. E. Medall & Associates, Inc. County of Los Angeles November 7, 1978 Page 7 W. 0. 605D Cut Areas Excavations for cut lots are presently restricted primarily to the area of Lots 63, 64, and 67, Tract 29053. The buttress backcut in this area is down approximately 30 feet. The cut portion of the 70 foot high fill -over -cut slope above Lot 76-79, Tract 34160, has been constructed as planned. OCTOBER 9 - OCTOBER 23, OCTOBER 23 - NOVEMBER 6 Buttress Keys The following buttress keys have been excavated, inspected, mapped and approved by a geologist from this office. Location Width (Ft.) Depth (Ft.) South of Lot 79 &,Offsite Tract 29053 15 3 Lots 53-55 Tract 29053 55 3 Lot 58 Tract 34161 55 3 South of Lots 59, 60, 63 & 64 Tract 29053 100 7 Lots 20, 22-28 Tract 29053 30 3 Lots 53-55, Tract 29053 Lots 58-60, Tract 34161 55 3 S. E. Medall & Associates, Inc. County of Los Angeles November 7, 1978 Page 8 W. O. 605D Fill Areas Fill materials are currently being placed in.the following Lot areas: Lots 49-52, Tract 29053, Lots 47-57, and 59-63, Tract 34161. Fill lots believed to be within one foot of final pad grade are presented as follows: Lots 5-8, 20--48, and 60-.93, Tract 29053. Cut Areas Excavations for cut lots, streets and slopes are currently restricted to the following areas: Lots 61-77 and 100, Tract 34161. Geologic Conditions Geologic conditions, including bedrock structure, are generally conformable with the data presented in our previous reports References 6 and 8). Closing 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 practice in the fields of soil mechanics, S. E. Medall & Associates, Inc. County of Los Angeles Page,9 November 7, 1978 W. O. 605D foundation. engineering and engineering geology. This warranty is in lieu of all other warranties, either expressed or implied. Respectfully submitted, byqJohn J. eButelo Project Geologist S. E. MEDALL & ASSOCIATES, INC. JJB:LFA:WRM:sm Reviewed by Ze-,r- Luis Fernando Aragon, <.C.E. 26 Principal Engineer S. E. MEDALL & ASSOCIATES, INC. Reviewed by'\ tU,`1,at / I`--il\tn- -- . Wil',11-a'm- R. Munson; C E.G. 866 Principal Engineering Geologist S. E. MEDALL & ASSOCIA ES, INC. C: (2) Addressee 1) Weatherfield Homes, Inc., Attention: Mr. Glen Bringle 1) VTN Consolidated S. E. Medall & Associates, Inc.