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HomeMy WebLinkAboutCT 76-17; La Costa Vale Unit 2; Soils Report; 1973-01-01.‘~ ‘I ~“,C -. T. FUNNEKOTTER ENGINEERING GEOLOGY - tmSTERED GEOLOtlST CER,xlFlEC ENGINpNG GEOLOGIST P. o.J,ox 575 ESCONDIDO. CALIF. 92025 746.2793 - - - - - - - - - - - - - - Benton Engineering Inc. 6741 El Cajon Blvd. San Diego,Calif. 92115 Attn: P. Benton GEOPHYSlCN IN”ESTlGATIONS For S”bdi”iSi0” Design Pipelinel Roadr Seismic Rippability Studier January 1,1973 Dear Sir, Enclosed is the Subsurface Investigation Report of LaCosta Vale - Unit 2 - lines Al6 thru E16. Original velocity profile of these lines is also included. Very truly yours, T. Funnekotter ENGINEERING DEFT. LfBRARY City of Ca!fspad 2075 Las PalmasWve Carl&ad, CA 92009-48~59 - .i - T., FUNNEKOTTER ENGINEERING GEOLOGY REGlSTERED GEOLOtlST CERTlFlED ENGINEERING GEOLOGIST P. 0.90x 575 ESCONDIDO, CALIF. 92025 746.2793 SUBSURFACE INVESTIGATIOM LA CCSTk VALE - UNIT 2 ShIkXE.IC LINES Al6 THRU El 6 January 1,1973 GEOPHYSICAL IN”ESTICAflONS For S”bdi”i,iO” D&g” Pipelines Roods Seismic llippability Studier - - - - - - T., FUNNEKOTTER ENGINEERING GEOLOGY GEOPHYSICAL IN”ESTIGATIONS REGISTERED GEOLOGIST For CERTlFlED ENGlNEERlNG GEOLOGlST Subdivision Design P. 0. 80X 575 ESCONDIDO. CALIF. 92025 Pipeliner bx!r 740.2793 Seirmic Rippobility 3udier Purpose: Method: Discussion: To evaluate subsurface conditions in three select areas in order to determine what excavation problems may be encountered. Refraction Seismography. Geologic reconnaissance. The Seismic traverses are in the Black Mountain Vo1cani.c unit - the material ranges from andesite to rhyolite. This report includes lines A16,B16,C16, D16,and El6 - located approximately as shown on the enclosed plat. In general, three velocity zones were mapped as follows: Velocity Range (ft/sec) Material 1300 to 2000 Soil & fill 2800 to 4200 Decomposed & fractured volcanic 7500 to 10,000 Hard, rigid volcanic Lines A each other from 12 fe 16,Bl6, and Cl6 are in one area and cross . High velocity volcanics were located here et to 26 feet deep. The intermediate layer of decomposed and fractured volcanics has a velocity range of 2800 to 4100 ft/sec. The upper soil layer has a velocity range of 1300 to 2000 ft/sec and is up to 12 feet deep. Kost of the high velocity material in this area appears to fall between a depth of 12 feet and 20 feet. The area immediately west of line Cl6 has T; FUNNEKOTTER ENGINEERING GEOLOGY REGISTERED GEOLOGIST CERTlFlED ENGINEERING GEOLOGIST P. 0,.80X 575 ESCONDIDO. CALIF. 92025 746.2793 - GEOPHYSICAL IN”ESTIGATIONS For sutdvirion Design Pipeline* Rood, Seismic Rippobility Studier Discussion: (can't) a considerable amount of rubble and boulders on the surface. Line D16 is in the second area. high velocity volcanics were located here at 28 to 32 feet. The intermediate zone velocity here measured 3500 ft/sec. Line Elf: is in the third area investigated and indicates high velocity material at 17 feet. The overburden velocity here is 42OC ft/sec. All runs indicate the presence of boulders and blocks in various degrees of profusion. Some of these are q,uite large, especially so where indicated on the profile. These blocks appear to be most concentrated in the area of line Cl6 and the northwest end of line 1;16. Conclusion: Hard, rigid volcanic material was located on all Seismic runs. The depth of this material is from 12 feet to 32 feet - mostly falling between 12 and 20 feet. The overburden velocity falls within a range of 2800 to 4200 ft/sec. In terms of rippability, based on a D-o Cat, the following schedule should apply: - - - - - - T., FUNNEKOTTER REGISTERED CEOLOGlST CERTIFIED ENGINEERING GEOtOtlST P. 0. 80X 575 ESCONDIDO. CALIF. 92025 746.2793 ENGINEERING GEOLOGY Conclusion: (can't) Velocity (ft/sec) 0 to 2000 2000 to 5000 5000 to 5500 Over 5500 GEOPHYSICAL lN”ESTlGATlONS For S”bdi”iaion Design Pipelines Roadr Seismic Rippobility Studier Excavation Nethod Scraper Ripper Marginal Drill & Shoot For trenching, based on a Kohring 505, the following should apply: Velocity (ft/sec) Excavation Method 0 to 3GOO Ripper 3800 to 4300 Marginal Over 4300 Drill & Shoot Submitted by .- &+V- 7$& i;_cL,>J~:& < ,c 1-i -I-.- 'I'. Funnekotter - -.. . ,,_ . l~‘J .‘.. - \ I, “‘.~.. ,~ / ‘Y. --A.’ - - - - \ 4. Z+G i \ I ,. ~~. ~--y (g-Q) .,__., \ \ +I i ‘- I L ,,)“#i4’:’ ../ ‘, /lb’ r F’ - pi& _~ .~ ‘oJ $2 ’ t’ L \ ‘y,,, (f i . . ‘. A._ oi Q@ .:l’+si, / ’ I. :I~ .‘LJ ‘-1 ._ . .-*.Y Y..‘ ‘1. --., \ ‘\ ‘\ ‘\. - j-;~ N li& / ‘/~ .- ;’ <; i; ‘-j 7 , ,’ SLISi%IC - RIPPABILITY Ii9FORMATION - - - The following points should be considered when evaluating Seismic information: 1. All velocities, depths, and thicknesses are averages and qualified according to the following schedule: G - good F- fair P - poor VP - very poor ? - questionable Grades of G, F, and P can be considered reliable; VP and ? should be considered as indi.cations only. 2. Each profile provides information in the immediate area of that profile - extrapolation outward from this area must be considered speculative unless additional information is available. 3. As the velocity of the material increases, ripping becomes progre- ssively more difficult until at some point it is more economical to drill and shoot the material prior to excavation. This point occurs within the marginal zone. Rippability figures vary with the type of material, however, in general, B-9 ripper performance is as follows: Velocity Range (ft/sec) Excavation Method 0 to 2000 Scraper 2000 to 5000 Ripper 5000 to 5500 Marginal Over 5500 Blasting These figures are based on several hundred job studies. 4. For trencher and backhoe operations the rippability figures must be adjusted downward, i.e., velocities as low as 3500 ft/sec may indicate material that is not rippable, depending on the homogeneity of that material, whereas material measuring over 4300 ft/sec almost certainly would require explosive work. As an average, materials measuring over 3800 ft/sec would mean difficult trenching and the economics of the situation would probably dictate explosive work first, The above figures are based on a machine similar to the Kohring 505.