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Home My WebLink AboutCT 72-20; La Costa Vale; Soils Report; 1973-02-26CT. -.-___--..~.. -~~__ __~ - .~ -- ., ‘I *’ ‘:i ” f? ,s.c cr - __‘~ Cq---l2-~0 ‘i 6‘~ _, ,+:‘. I T.:.,FUNNEKOTl’EJt ENGINEERING GEOLOGY GEOPWSICAL IN”ESIIG*TIONS REGISTERED GEOLOGIST For CERTIFIED ENGINEERING GEOLOGIST Sutdivi,ion cmipn p. q. BOX 575 EscONDIDO. CALIf. 92025 Pipelines Roads - 746.2793 shmic Pippobility St”di.l - - - - - - - - - - - - - - - Denton Engineering Inc. 6717 Convoy Ct San Diego,Calif. 92111 Attn: Bob Remer February 26,1973 ,,. 11. Dear Sir, Enclosed is the Subsurface Investigation Report of La Costa Vale - Seismic lines Al7 thru 517. Also enclosed is the originals of the Seismic profiles of these lines. If there are any maps which can locate the stake I mention near line 517 this would help to locate the position of this line. This stake. is a 2x2 painted white with the upper part painted red and tied down with wire. If you have any qestions please call. very truly Y”~ Ted Funnekotter ENGINEERING DEPT. LIBRARY City ol Carlsbad 2075 Las Palmas Drive Carlsbad CA 92009-4859 .- T. PuNNEKO-I~ER ENGINEERING GEOLOGY GEoPwsIcAL INVESTIGATIONS FzEG,STE@ED GEOLOGlST hx CERfWIED ENGWEERING GEOLOGIST S”bdi”iSi”” Dosign P. Q, BOX 575 ESCONDIDO, CALIF. WC05 Piplim Road, - 746-2793 seimic Pippobility Studies - - SUBSUKPACE IIiVEsTIGATION LA COSTA VkLi -. SEISMIC LINES A17 THRU 517 February 26,1973 - - - - - -~ - - .- - .- T.: FUNNEKOTTER ENGINEERING GEOLOGY GEOFtlYSlCAL IN”ESTICATIONS REGISTERED GEOLOGlST For CERTIFIED ENGlNEERlNC GEOLOGIST S”bdi”irion carig” P. 0. BOX 575 ESCONDIDO. CALIF. 92025 Pipeline, Pod, 746-2793 kismi~ Pippbili~ Studi., PURPCSE: To evaluate subsurface conditions in nine select areas in La Costa Vale in order to determine what excavation problems may be anticipated. METHOD: Refraction Seismography. Geologic reconnaissance. DISCUSSICK: The areas investigated are all within the Black Eountain Volcanic structure - this unit is principally extrusive igneous flows ranging from andesite to rhyolite. The layer sequence is soil, decomposed and fractured volcanics with sparse to heavy concentrations of volcanic blocks within the overburden, and the parent volcanic rock. Ten lines were investigated by the Seismic method - lines Al7 thru 517. The approximate location of these lines is shown on the enclosed plat. The location of lines H17, 117, and J17 should be considered as very general - no good distinctive features here permit very accurate orientation. However, note on the plat the position of a red-white stake near the southeast end of line J. All other lines were oriented from high voltage towers or poles and distinctive topographic features. In general, high velocity volcanics were located on all of, the Seismic runs. The depth of this material is from l+.feet to I+$ feet. The intermediate layer has a velocity range of 2500 to 4800 ft/sec - averaging around 3600 ft/sec. The soil layer is from 2 feet to -- -_-- ~. -~ - - ,- - T. FUNNEKOTTER ENGINEERING GEOLOGY REGISTERED GEOLOGIST CERTIFIED ENGINEERING GEOLOGIST P. 0. BOX 575 ESCONDIDO, CAM. 92025 746.2793 GEOPHYSICAL INVESTIGATIONS For Subdivirion Design Pipelins. hods seirmic aippakmy S,udi.* DISCUSSICN: 9 feet thick. Line Al? indicates from 25 to 29 feet of over- burden (3800 ft/sec) over 10,000 ft/sec volcanics. Cn line B17, the high velocity volcanics rise from 24 feet to 12 feet from the surface and has an over- burden velocity of 3100 ft/sec. Line Cl7 shows the high velocity volcanics from 23 feet to 48 feet deep, howaver, note the overburden velocity from station 0 to station 1.5 - it was 4800 ft/sec in this area. This is approaching the marginal rippable category of 5000 ft/sec. Line D17 shows high velocity material rising steeply towards the east and southeast - from about 40 feet deep to 12 feet deep. Lines E17, F17, and Cl7 are all in one general area and show the'hard volcanics to be from 4 feet to 29 feet deep, mostly quite shallow. The overburden velocities here range between 3300 and 4200 ft/sec..This hard volcanic horizon appears to rise towards the southwest and northwest. Cn line G17, this layer is very shallow - from 4 to 9 feet deep. Lines H17 and 517 are on a northwest trending ridge and the high velocity material here appears to be roughly confcrmable to the surface. Note the rise and fall of this material across line H17 and the rise along line J17 towards the southeast. Line Il7 indicated high _- ~-- .-, _~~ _-. --.- .~- - - T. FUNNEKOTTER ENCjlNEERlNG GEOLOGY GEOmw.lCAL IN”BTlt*nONS PEGlSTEPED GEOLOGIST CERTlFlED ENGlNEEPlNC GEOLOGIST I PO, S”bdi”irion Derign P. 0. BOX 57s ESCONDIDO. ‘ALIF 9202s Pip.lin*r lloadr - 746.2793 SeiMiC Rippobility Studier - - DISCUSSION: velocity material at a depth oa approximately ?2 feet. The overburden in these areas contain volcanic - - blocks in various degrees of concentration - this is so indicated on the profile. CONCLUSION: The most troublesome areas in terms of near surface hard volcanics appear to be lines G17, F17, the soutb- - - - - - - - - - - ,~- eastern end of line Dl7 and the area around lines Hl7, 517, and 117. In much of these areas the high velocity volcanic material is less than 10 feet deep. In terms of rippability, based on a D-9 Cat, the following schedule should apply: Velocity (ft/sec) Excavation Method 0 to 2000 Scraper 2000 co 5000 Ripper 5000 to 5500 Marginal Cver 5500 Drill & Shoot For trenching, based on a Kohring 505, the following schedule should apply: Velocity (ft/sec) Excavation Method 0 to 3800 Rippable 3800 to 4300 Marginal Over 4300 Drill & Shoot Submitted byes&. T. RunneRotter