Loading...
HomeMy WebLinkAbout; La Costa Valley Unit 3; Soils Report - Compacted Filled Ground; 1965-10-13BENTQN ENGINEERING. INC. *PPL.,ED eo,c MECHANICS - FO”ND*TIONS 674, EL CAJON BOULEVARD *AN DIE00, C*LIFORNI* *21*s October 13, 1965 Paradise Homes, Inc . Route 1, Box 2550 Encinitas, California Subject: Project No. 64-6-18D Final Report on Compacted Fi I led Ground Lots’141 to 143, inclusive Co Costa Valley Unit No. 3, San Diego County, California Gentlemen: This is to report the results of tests and observations made’in order to inspect the compaction of filled ground placed on certain areas of Lots 141 to 143, inclusive, of La Costa Valley Unit No. 3, San Diego County, California. The fills,were placed during the period between August 12, 1964 and December 11, 1964. The approximate areas and depths of filled ground placed under our inspection; in accordance with the approved specifications, are shown on the attached Drawing No. IA, entitled, “Loca- tion of Compoc ted Fi I ied Ground. ” The tentative map of La Costa Volley Unit No. 3 was prepared by Rick Engineering Company and dated August 23, 1965. The results of expansion tests performed on representative samples of soils existing at near finished grade are presented on page 4. The approximate locations at which the tests were taken are shown on Drawing No. lA, and the final test results are presented on page 3, under the “Table of Test Results .I’ The laboratory determinations of the maximum dry densities and optimum moisture contents of the maior fill materials are presented on page 3, under the “Laboratory Test Results.” The tests were taken during the weekly periods indicated below: Test Number Week Ending 1 to 9, inclusive August 15, 1964 10 to 16, inclusive August 22, 1964 17 to 21, inclusive December 12, 1964 SlOlO - . ’ - - ,~- - - - - - .- -. - - - t* ., I*, - . -1% j . ,, ‘. ___-.- ’ i Reject No. 64-6-18D ’ Page 2 October 13, 1965 La C&ta Valley Unit NO. 3 1 fThf I e ina results of tesk and observations indicate that the compacted filled ground has been ; j placed at 90 percent of the maximum dry density or~greater . It has been determined that the fill materials, compacted to 90 percent of the maximum dry density, hove a safe bearing value I of at least 1050 pounds per square foot for one foot wide continuous footings founded at a I minimum depth and placed five feet or more inside the top’of compacted filled ground slopes. 1 If footings are placed closer to the exposed slopes than five feet inside the top of compacted filled ground siopes, these should be deepened.one foot below a 1 l/2 horizontal to l’vertical line projected outward and downward from a point five feet horizontally inside the top of compacted filled ground slopes. The results of expansion tests indicate that the soils existing at or below finished grade on the subject lots would .be considered as exwnsive. It is therefore recommended that footings and slabs be designed as recommended in our report entitled, “Recommendations for Footings for Soil Conditions on La Costa Volley Unit Nos. 1 and 2.:“) Uncompacted filled ground was placed on certain nonbuilding areas in Unit No. 3. The locations of these areas are shown on Drawing No. 1. Respectfully submitted, ,! BENTON ENGINEERING, INC. / By&&&a- R. C. Remer ilip t4’. Benton, Civil Engineer j Distr .: (4) Addressee I (2) Director of Building Inspection t (I) Rick Engineering Company I (1) Mr. Burt Kramer I)LNTOH LNOINEERINO. INC. - - - - - - - PH,L,P HENKING BENTO,N PREIIOLLI, ClVli c”tilnELR BENTON ENGINEERING, INC. APPL,ED SOlL MECHANICS .--- FO”N”ITlOiiS 674‘ EL CAJON DO”LEYAA0 SAN D,LGO. CALIFORNIA 8.2115 December 8, 1964 S&H DIEGO: 583-5654 LA MEa*: 469.c.614 Paradise Homes, Inc. Route 1, Box 2550 Encinitas, California Attention: Sub[ect: / i Gentlemen: Mr. Irv Roston ProjecF No. 64-6-18D Recommendations for Footings for Soil Conditions on. La Costa Valley Unit Nos. 1 and 2 San Diego County, California It is concluded from correlating the laboratory test resulk presented with our “Final Report on Compacted .tilled Ground, La Costa Unit Nos. 1 and 2, San Dicgo County, California”, dated November 25, 1964, with the visual observations made during grading and in classifying the soils in expldration borings drilled upon completion of gradi@ that the soils within the upper three feet on the lots fall within two major categories listed below: M:rginally Expansive Expansive Unit NO. i - Lok 4<< 48, 49, and 52, 53, 54, a:, and 56, 60, 72, 73, and 74, 76, ‘_ 79, 80, and 81, 84 to 69, inclusive 93, 95, 96, 99, 100, and 101, 106, 108, 109, 110, 111, 127, 128, and 131, Condominium Areas C and D Unit No. 1 - Lots 44, 45,.,46, 50, 51, 57, 58, and 59, 7j,j inclusive,’ 75, 77, and 61 to 78, 82, 83; 90, 91, and 92, 94, 97, 98, 102 to 105, inclusive, 107, 112 to 119; inclusive, 130, 132, and 133, Model Lok 122 to 126, inclusive, and 129, Condominium Areas A, 8, E, F, H, I, and J. ‘Unit No. 2 - Lot 139 (3-10-67) UnitNo.2- Lok 135, 136, 137 and 140 (3-10-67) It is concluded from our past experience in areas where .solls fall into these two general cate- gories that continuous wall footings should be used throughout and that these should, be placed c.ti varying depths and reinforced to varyin@ degrees depending upon the volumetric change with change in moisture content of the supporting soils. Also, if concrete slabs are to be . -_ - - - - - - - - - ., Project No. 64-6-18D -2- December 8, l,a Costa Volley Unit Nos. 1 and 2 ” 1964 placed on the “expansive” soils, it is recommended moisture tests be taken 4 to 5 weeks prior to pouring concrete to verify that 80 percent saturation of the layers exrst, ~.:“;~-Qz~p~m3 feet ” If less moisture exists, then presaturation would be recommended, The reason for this is that concrete slobs arc relatively lightly loaded in comparison to continuous wall footings support- ing raised wood floors and they ore subject to much greater upward movement if the “expansive” clays go from a relatively dry field condition to neor saturation thon ore the wall footings that are placed at greater depths below the finished ground surface. Numerous tests and cbservo- tions made to dote indicate that the “expansive” soils tend to increase in moisture content with time, once these ore covered and lawn watering, etc. ta&es place around the perimeter of the foundation. Houses constructed in the spring when the soils have notural presaturntion have proved to show far less differential movement than houses constructed on air dry soils without presoturation in the fall of the year. The foltowing recommendations are made for the two cotegroies of soils listed previously: ,, ‘1’ . !’ ,;” I. Type of Consiruction of Raised Wood Floors on Continuous Wall Foundations, A. For Marginally Expansive Soil Conditions I. Place footings at minimum depth ofone foot. 2.~, Reinforce with one #4 steel’ bar placed at three (3) inches above the bottom of the continuous wall footings ond one #4 steel bar placed at one and one- half (1 l/2) inches below the top of stem wall of the footing. It is Irecommended that the steel reinforcement of all interior and exterior con- tinuous wall footings be lapped 48 diameters and thot the reinforcement of the interior footings be carried into the exterior walls sufficient distance to de- velop full~strength. 4. Construct crawl holes with continuous reinforcement as shown on page 17 of the “Minimum Property Requirements for properties of one or two Living Units, Located in the Southern California District” by the Federal Housing Adminis- tration Revised May 1952 or by some equivalent design. For c&Crete slabs on ground in the garages, it is recommended that a 4 inch thickness of sand be placed beneath the c,mcrete slab ond that the concrete slabs be separated by 3/B inch thickness of construction joint material from the exterior wall Footings. The slobs should also be reinforced with 6”-6” by #lo-#10 wire mesh. B.U or Ex ansive Soil Conditions Place footings at a minimum depth OF two feet. Reinforce with one g.5 steel bar placed three inches above the bottom of Footing bar placed 1 l/2 inches below the top of stem wall of the Footing. BeNrON ENOINEEHING. INC, -_ >- - - - - - . Project No. 64-6-18D Lo Costa Valley Unit Nos. 1 and 2 -3- December 8, 1964 3, 4, and 5. Some as fa Section .A obave. II. Type of Construction of Concrete Slab Floors on Ground Between Continuous Wall Foundations A. For Marginally Expansive Soil Conditions 1. Place footings at a minimum depth of one foot. 2. Reinforce tith one #4 steel bar placed at three (3) inches above the bottm of the continuous wal I footings and one f.4 steel bar placed at one ond one- half (1 l/2) inches below the top.of stem wall of the footing. -. 3. It is recommended that the steel reinforcement of all ‘interior and exterior con- tinucvs wall footings be lapped 48 diameters and thot the interior reinforcement be carried into the exteriw walls sufficient distance to develop full strength. 4. .The concrete slabs on ground inside the houses should be placed on a minimum of 4 inches of sand and reinforced with 6”-6” by SlO-#lO wire mesh. A woter- proofing seal under, within, OT on top of slob should be provided. 5. For concrete slobs on ground in the garages, it is recommended that a 4 inch thickness of sand be placed beneath the concrete slab and that the concrete slabs be separated by 3/8 inch thickness o the exterior wall footings. The slabs shou #IO-#10 wire mesh. lace footings at a minimum depth of two feet. einforce with one #5 steel bar placed at three (3) inches above the bottom of the continuous wol I footings and one 15 steel bar placed ut one and one- half (1 l/2) inches below the top of stem wall of the footing. a 3. I is recommended that the steel reinforcement of all interior and exterior con- inuous wall footings be lopped 48 diameters and that the interior reinforcement 0 be carried into the exterior walls sufficient distance to develop full sfrength. 4. For concrete slabs on ground for this condition, it is recommended that field moisture checks be made to three feet below finished grade to verify_8Qer- cent saturation. t80 Ercent soturotion is-sent, then it i,s~~>~$d me added’q PG~C-‘~~ “rain bards” or ony suitable method to in- ‘. crease moisture a: required. After the presaturation moisture content is achteved within the upper three Feet, the soil may be permitted to surface dry so that equipment may work on it and then the 4 inch sand layers should be deposited BCNTON ENOINEERING. INC. -. .* , ---rl-I-.“y~ I- ---;” ,._,._,, _ ,,.; ..l--.~‘l~=‘~~-nr- =~i~~=~~~j.,~~ -= . --~-=-mmwi_l ,‘-;““;---,~,, P---m;- , - - - 1 Project No. 64-6-18D I L4- December 8, 1964 Lo Costa Volley Unit Nos. 1 and 2 - - - - within one week. The reinforcing with 6”-6” by #IO-l10 wire mesh ond water- proofing may then be installed to seal the presaturoied soils under the concrete slabs. /r? 5. For concrete slobs on ground in the gorages, Q/ it is recommended that a 4 inch thickness of sand be placed beneath the concrete slob and that the concrete slabs be separated by S/8 incll thickne:: of construction ioint moterial from the exterior wall footings. TI w slabs should also be reinforced with 6”-6” by #1O-!11O wire mesh. __Iu.e.- ---=-e _,I If you should hove any questions regarding the above, or if you shmld dczire additional inFol-- matim, pleose feel fl-ee to contact me. Very truly yours, BENTON ENGINEERING, INC. - PHB/gw .: .T-yRI;~ 1;: _‘~~ ..---cnmr-v! ,,~ ~ I-F-cF~-- .~. ~~__4c_ -,--. _ _:_,. ~~~~ .,,.. .~.. - - - -- - - - - - - - - - BENTON ENGINEERING, INC. APPLIED SOIL MECH*N,CS - FOUNDATIONS 6741 EL C*JON BOULEVARD **I4 DIECIO. CALIFORNIA e2115 October 13, 1965 PHlLlP HENKING BENTON *AN DILG.: e*s.ses4 PlE*loENT CIVIL ENGIYEeR LA MTSA: 46S-S8S4 Paradise Homes, Inc. Route 1, Box 2550 Encinitas, California Subject: Project No. 64-6-18D Final Report on Compacted Filled Ground Lots 141 to 143, inclusive La Costa Valley Unit No. 3, San Diego County, California Gentlemen: This is to report the results of tests and observations made in order to inspect the compaction of filled ground placed on certain areas of Lots 141 to 143, inclusive, of La Costa Valley Unit No. 3, San Diego County, California. The fills were placed during the period between August 12, 1964 and December 11, 1964. The approximate areas and depths of filled ground placed under our inspection, in accordance with the approved specifications, are shown on the attached Drawing No. lA, entitled, “Loca- tion of Compacted Filled Ground .I’ The tentative map of La Costa Valley Unit No. 3 was prepared by Rick Engineering Company and dated August 23, 1965. The results of expansion tests performed on representative samples of soils existing at neor finished grade are presented on page 4. The approximate locations at which the tests were taken are shown on Drawing No. lA, and the final test results are presented on page 3, under the “Table of Test Results .‘I The laboratory determinations of the maximum dry densities and optimum moisture contents of the moior fill materials are presented on page 3, under the “Laboratory Test Results.” The tests were taken during the weekly periods indicated below: - - - Test Number Week Ending 1 to 9, inclusive August 15, 1964 10 to 16, inclusive August 22, 1964 17 to 21, inclusive December 12, 1964 - - - -. - - - - - - - -’ Project No. 64-6-181) La Costa Valley Unit No. 3 Page 2 October 13, 1965 The final results of tests and observations indicate that the compacted filled ground has been placed at 90 percent of the maximum dry density or greater. It has been determined that the fill materials, compacted to 90 percent of the maximum dry density, hove a safe bearing value of at least 1050 pounds per square foot for one foot wide continuous footings founded ata minimum depth and placed five feet or more inside the top of compacted filled ground slopes. If footings are placed closer to the exposed slopes than five feet inside the top of compacted filled ground slopes, these should be deepened one foot below a 1 l/2 horizontal to 1 vertical line projected outward and downward from a point five feet horizontally inside the top of compacted filled ground slopes. The results of expansion tests indicate that the soils existing at or below finished grade on the subject Iok would Abe considered as expansive. It is therefore recommended that footings and slabs be designed as recommended in%Zreport entitled, “Recommendations for Footings for Soil Conditions on La Costa Volley Unit Nos. 1 and 2.“‘ Uncompacted filled ground was placed on certain nonbuilding areas in Unit No. 3. The locations of these areas are shown on Drawing No. 1 . Respectfully submitted, ’ BENTON ENGINEERING, INC. BY -tQ e i?9zLde R. C. Remer Reviewed by Philip W. Benton, Civil Engineer Disk.: (4) Addressee (2) Director of Building Inspection (1) Rick Engineering Company (1) Mr. Burt Kramer - - - - - BENTON ENGINEERING. INC. I .” - - - - - I - - - - - - - - - - - - Project No. 64-6-18D La Costa Valley Unit No. 3 Page 3 Test Lot No. No. 1 143 2 2 143 2 3 143 4 4 143 4 5 142 2 6 141 2 7 142 4 8 142 4 9 143 6 10 143 6 11 141 6 12 143 8 13 142 8 14 142 10 15 142 6 16 141 10 17 141 1 18 141 3 19 141 5 20 141 2 21 141 7 Depth of Fill at Test in Feet TABLE OF TEST RESULTS Field Dry Maximum “r~ Moisture Density Density % dry wt lb/c” ft lb/w ft 8.7 109.3 118.6 11.8 109.6 118.6 13.7 112.4 123.2 11.2 105.2 114.0 12.0 119.0 124.9 14.5 103.2 111.3 16.2 107.9 119.1 9.7 106.2 115.8 14.2 106.8 116.5 10.7 106.2 114.0 19.2 99.0 109.6 13.6 119.2. 123.2 11.1 105.8 115.8 12.7 103.0 111.1 13.1 108.6 115.8 10.7 101.8 111.1 12.1 102.5 114.0 14.1 104.0 112.9 12.5 97.8 107.6 15.2 99.0 107.9 17.1 97.6 107.9 LABORATORY TEST RESULTS October 13, 1965 Percent Compaction Remarks 92.2 92.4 91.1 92.2 95.3 92.7 90.5 91.6 91 .6 93.1 90.3 96.7 91.5 92.6 93.8 91.5 90.0 92.2 90.8 91.8 90.4 At Grade At Grade At Grade At Grade The maximum dry densities and optimum moisture contents of the maior fill materials, as deter- mined by the A.A .S .H.O. T99-57 method, modified to use 26 blows of a 10 pound hammer falling from a height of 18 inches on each of 3 layers in a 4 inch diameter l/30 cubic foot compaction cylinder, are presented as follows: Maximum Optimum Mois- Dry Density ture Content Soil Type lb/w ft % dry wt Brown silty fine sand, clay binder 123.2 10.5 Dark gray clayey silt, lime streaks 105.2 19.5 Brown, red-brown silty,clay 114.0 15.4 Light brown clayey fine to medium sand (lime streaks) 119.0 13.0 Gray-brown silty clay (% expansion = 12.4%) 111.3 14.8 Light brown very fine sandy silt 108.2 16.7 Dark brown silty fine to medium sand, clay binder 124.9 10.4 few gravel BENTON ENGINEERING. INC. - - - - -’ - - - - - - - - Project No. 64-6-18D La Costa Valley Unit No. 3 Page 4 October 13, 1965 Laboratory Test Results (Cont .) Maximum Optimum Mois- Dry Density ture Content Soil Type lb/c” ft % dry wt Light yellow-brown very fine to fine sandy clay 107.9 18.1 Silty fine to coarse sand 111.9 11.7 Yellow very fine sandy silt 110.0 16.5 Light gray silty fine sand 115.8 14.7 In addition to the preceding laboratory tests, expansion tests were performed on some of the clayey soils encountered to determine their volumetric change characteristics with change in moisture content. The recorded expansions of the samples are presented as follows: Location Lot 141 Lot 143 Depth of Sample Below Grade Percent Expansion Under Unit Load of 500 Pounds per Square Foot from Air Dry to Saturation 1 .o 5.54 1.0 13.25 BeNrON ENOINEERINO. INC.