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Home My WebLink AboutCT 72-03; TRI-CITY AUTO PLAZA; SOILS REPORT; 1972-12-14. , • BENTON ENGINEERING. 'INC. APPLIED SOIL MECHANICS -FOUNDATIONS 6741 EL CAJON BOULEVARD SAN' DIEGO. CALIFORNIA 92115 PHILIP HENKING BENTON" PR~SIDENT • CIVIL ENGINEER December 14, 1972 La Costa land Company Coita, De I Mar Road Rancho La Costa, California. 92008 Attention: Subject: . Gentlemen: Mr. BOb Stork Project No. 72-12-4F' Soils Investigation for Plaza del Norte between Trl-City Auto Plaza and Palomar Airport Road Carlsbad; California SAN DIEGO, 583-5654 LA MESA, 4t;i9-5654 This is to present the results of a soils investigation conducted in the proposed Plaza del Norte roadway extending from the Tri-City Auto Plaza to Palomar Airport Rood in Carlsbad, California. Th~ objectives of the investigation were to determine the existing, soil conditions along the proposed roadway and to present recommendations for the placement of compacted filled ground. F i,lq Investigation Five exploration pits were excavated with a backhoe to depths of 5.5 to 1200 feet below the existJng ground surface. A c,ontinuQus log of t.he soils encountered in the pits was ,recorded at the time of excavation and is shown in detail on Drawing Nos. 1 to 4, inclusive, each entitled IISummary Sheet. " The soils were visually classified by field identification procedures in accordance with the Unified Soil Classification Chart. A simplified description of this classification system is presented in the attached Appendix A at th~ end of this report. In-place field density tests were token at various locations in the undisturbed natural soils using the sand displacement test method and the results of the tests are presented on Drawing Nos. 1 to 3, . tnc lusive, each entitled "Summary Sheet. II Loose bog samples were obtained of the representative soils and were transported to the laboratory for testing. Laboratory Tests " The maxil'rum dry densities ar1ch)ptimum ma'isture contents of the 'representativesoi Is as determined . by the A.S .. .T .M. 0 1557-66T method, that uses 25 blows of a 10 pound rammer falling from a Project No. 72-12-41= .. La Costa Land Company • -2-• December 14,1972 height of 18 inches on each 9f 5 layers in a 4 inch diameter 1/30 cubic foot compaction cylinder, are presented as fa I lows: Bag .v.oximum Optimum ,\-\ois- Pit Sample Depth Dry Density ture Content No. No. in Feet Soi I Description Ib/cu ft % dry wt 1 2 1.8 -2.3 Si Ity fine sand '119.9 8.7 3 1 2.0 -2.5 Fine sandy clay 126.4 10.9 3 2 4.0 -4.5 Clayey fine sand 126.1 9.2 4 3 6.0-6.5 Silty clay 115.0 12.4 The relative densities of the soils at certain locations, based on the above maximum dry d~nsities, are presented on Drawing Nos. 1, 2, and 3. Discussion and Recommendations loose silty fine sand topsoils were found to depths varying between 005 foot oncl2.0 ~eet below the existing ground surface at Pit Nos. 1, 3, 4, and,S. Firm fine sandy clay topsoil was encountered to 1.0 foot in Pit No •. 2. The topsoils were underlain by mediu~ firm to v~ry firm silty fine sands, fine sandy clays, clayey fine sands, and silty clay. Free ground water was observed seeping from the sides of the exploration pits below depths of 5.0, 10.0, and 8.0 feet, respectively, in Pit Nos. 1, 3, and 5. Ground water was not encountered In Pit Nos. 2 dnd 4. Based on the determined relative densities ,of th~ soils existing below the loose topsOils, it is con- cluded that these medium firm to very firm natural soils will be adequate for support Qf the proposed roadway provided compaction of the upper subgrade soils is achieved in accordance with the requirements of the City of Carlsbad. ,It is recommended that all loose topsoils existing below proposed finished subgrade be removed and be replaced with filled ground uniformly compacted, to the relative densities as required by the City of Carlsbad. In order to prov ide more uniform and stable subgradesoi Is, it may bedesiroble to remove the fine sandy clay soils, such as found in the uppe~ portions of Pit Nos. ~, 3, and 4, existing within the upper 2.0 feet below proposed finished subgrade' and to replace th~se with properly compacted nonexpansive si Ity sand soils. It is our opinion that the existi round water conditions wili not b.detrimental t the construction of the roadwa~. However; I~ m~tyantictpated that dewatering will be required in certain areas during the placement of underground utilities. 'Respectfully submitted, BENTON ENGINEERING, INCo By' ¢.t~ ~..L-X- • 0 Remer @~ , I ,', Reviewed' / ~ I ' iij;:intOnliv~ " Distr: (4) Addressee BENTON ENGINEERING, 'INC. Z SUMMARY SHEET ... ,'-l t-0 tll. wcc ~ ...I II. .... w ...I(JO i ~I' gu:1 li:w ~~. m~ PIT NO· 1 ;3 ELEVATION 59.91 *' ~. ~ STA 34 =/= 07 Fill 3 .• 0· *1: -IOJ ~~ Dark Brown, Very Iv\::>ist, Loose, 1-~'\:.~ Topsoil to 1.8 Feet ; r2] ~~\:J-----------I ~ ~ Light Brown, Medium Firm, ;'.\.JJ ~~ Occasional Gravel i-~ .,... ~ Water ~ ~~~\7~~~~ ____________ ~ __ ~ ~~ Saturated - 6- -PIT NO. 2 - SILTY FINE SAND ELEVATION 59.2' r: STA.41 + 00 _ OJ 1 ......... ~"io1 Brown, lv1oist, Firm, Topsoil 1-to 1 Foot _ [I] Brown-gray, Very lv1oist, Very 2-_! f:\ Firm, Streaks of White and • \l.lJl~~~ Brown 3- 4--_ tB2' , j-:--'--='.f Gray-brown, Very Iv\::>ist, Very .. . Firm 5-: - 6- - 7"'; - · . · .' · . .. , FILL 1.0· FINE SANDY CLAY (Nterges) CLAYEY FINE SAND o -Indicates Loose Bag Sample - -o -Indicates Field Density Test - - 6.9 106.0 16.91104.0 14.21116.0 10.7)21.7 ,;... -* _ Elevations shown were obtained from the plans for the improvement of Plaza del Norte prepared. by Associated Engineers ~ - -** -Indicates proposed "grading. PROJECT NO. 72-12-4F BENTON ENGINEERING, INC. DRAWING NO. 1 . - 88.5 86.8 • Z > ... 0 0": >, W' Z w ~,~ SUMMARY SHEET o~~ ...... ' ut-,0 w wa: a: II. iii 'II. 11:211. II. ~w ~uo w_ z' .... 'Q.aI o-al zf ~j:> wa «d ,~i :t ~~ en~~ PIT NO. ;3 w_ Wena: wlnen ... <::l w~ ,0 .... ' :t-~ Q. ~> ii:oO >:g en en w enz ;;jen ELEVATION 6ELZ' :!..: ~~ w- 0 d STA. 50 + 00 ~ILL 0.51 a: II. ri'~ a:~ (). 0 ~~ Brown, Moist, Loose, Topsoil SILTY FINE ~u -..,.. 1\ SAND / 1--.; ;:-';" Brown, Moist, Medium Firm 2-lill FINE SANDY -Brown-gray, Very Moist, Firm CLAY 15.0 110.8 87.6 3---; ;-;' 4:'" Brown, Moist, Very Firm a3 -;-8.1 111.1 88.1 --;-~ , -;--;--;-, I-e:: -;-, ':;-, , '-; -'-~ , -";'-;- 6-CD ' , i , , , 7.1 111.7 88.5 --;--;- -;--;- 7-~ CLAYEY FINE -. SAND -;-', . 8--;--;-' ' " -"~ 9--; ,-; , ~~~ Very Moist 10"" --,-;-Saturated -, .', 11-, -;-.-, ---:-~ .. ;' y 12--.- ;S - - - -- - - .,... - - -- - -- - - -. , PROJECT NO, : DRAWING NO. 72-l2-4F BENTON ENGINEER'ING, INC. 2 • . -7: . . ~, 2 > Q"' ... 0 >, w' i=-1 0' e~~ ...... u'" rio w we: SUMMARY SHEET a:'" iij~. I-w w!!.:. z~ ~ ...Iw ...Iete z.~ ...I~~ 2:; ~«d I~~ ..... 0.11:1 _U'II:I P·IT NO. 4 :r: :E:E eii::E w_ !!!~~. Wu w"'~ I-ct:l (1)-> w~ 0,: :ten 0. (1)2 ~(I) 76.6 >' ~o >:g (l)u;1f ~8 w ELEVATION, _ ... ~~. w- e ct a:~ a:...I a:liI: ~ STAo 57 + 30 FJLL 0.1' e 0 0 ~ Brown, JIAoist, Loose, Topsoil SILTY FINE _. 1·-SAND 183 i~~X~~ _. Brown-gray, Very Moist, Very 2-Firm FINE SANDY 13.3 1116.5 ~ .:. ;'".' -CLAY 3- .~ 4 .... ffi · . Brown-gray, Very NIoist, Very 11 •. 5 ! 113.5 · ~ ~ CLAYEY FINE -;' 1~lrm ' 5 --.... SAND ... · .. 6-8j . Brown-gray, Very NIoist, Very -irm SILTY CLAY 21.4 105.( 91.3 7- -Gray-brown, Very Moist, Very 8 ~. Firm FINE SANDY CLAY -9 . ..; -"~ Brown, Moist, Firm 10~ ~ SLIGHTLY SILTY _. FINE TO M.EDIUM ~~~ SAND 11-i:'\~,,, .-~~ 12·· '0;,<' xx>; _ •. . - '" _. - .. '" - .. .--a-I- .~ - .-. _ . . - ... - - BEN~INE~R~~C. PROJECT NO. = ~.~ DRAWING NO. 72-12-41= 3 .. ., J .... . -y .~ f- '" ,., .1-0 w w II-""-:t I-a.. w 0 0 1 2 3 4 5 6 7 8 9 10 ilia: ..Jw ~IXI ~:e «:::l Cl)Z SUMMARY SHEET PIT NO 0 _5_, __ ELEVATION 57.7' loose, T opso i I "' ...... ,"'."'. Light Brown, Very tv\oist, Medium Firm, Occasional Gravel PROJECT NO. FilL 3.0' SILTY FINE SAND ANDY CLAY 72-12-4F BENTON ENGINEERING, INC. DRAWING NO. 4