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Home My WebLink AboutCT 72-20; La Costa Vale Unit 3 & 4 Trac 72-20 & 76-3; La Costa Vale Unit 3 & 4 Trac 72-20 & 76-3; 1977-02-04BENTON ENGINEERING, INC. APPLIED SOIL MECHANICS FOUNDATIONS 6717 CONVOY COURT SAN DIEGO. CALIFORNIA 82111 February 4, 1977 PHILIP HENKINO BENTON PRESIDENT - CIVIL ENGINEER La Costa Land Company 2100 Cos fa Del Mar Road Carlsbad, California 92008 TELEPHONE ( 714 Subject:Project No. 74-5-2D Final Report on Compacted Filled Ground La Costa Vale Unit Nos. 3 and 4 Carlsbad Tract Nos. 72-20 and 76-3 Carlsbad, California Gentlemen: This is to report the results of tests and observations made in order to inspect the compocUnn of. filledjground placed on certain areas of La Costa Vale Unit Nos. 3 and 4 in Carlsbad, California. "The fills were placed during the period between June 10, 1974 and January 24, 1977. Also included in this report are the results of tests taken in trench backfill placed over certain utility lines.i The approximate areas and depths of filled ground placed under our inspection in accordance with the approved specifications are shown on the attached Drawing Nos. 1, 2, and 3, each entitled "Location of Compacted Filled Ground." The grading plan used for the placement of filled ground, dated April 18, 1974, was prepared by Rick Engineering Company. • v The approximate locations at which the tests were taken and the final test results are presented on pages T-l to T-53, inclusive, under the "Table of Test Results." The laboratory determinations of the maximum dry densities and optimum moisture contents of the major fill materials are presented on page L-l, under the "Laboratory Test Results." Some of the maximum dry densities shown in the "Table of Test Results" wore combinations of these. The tests were taken during the weekly periods indicated below: Test Numbers 1 to 7 to 10 to 38 to 118 to 185 to 249 to 322 to 401 to 451 to 6, 9, 37, 117, 184, 248, 321, 400, 450, 473, inclusive inclusive inclusive inclusive inclusive inclusive inclusive inclusive inclusive inclusive Week Ending June 15, 1974 March 13, 1976 March 20, 1976 March 27, 1976 April 3, 1976 April 10, 1976 April 17, 1976 April 24, 1976 May 1, 1976 ,,May8, 1976 Project No. 74-5-2D La Costa Vale Unit Nos. 3 and 4 -2-February 4, 1977 Test Numbers 474 to 483, inclusive 484 to 496, inclusive 497 to 520, inclusive 521 to 545, inclusive 546 to 575, inclusive 576 to 608, inclusive 609 to 635, inclusive 636 to 675, inclusive 676 to 697, inclusive 698 to 743, inclusive 744 to 771, inclusive 772 to 811, inclusive 812 to 875, inclusive 876 to 925, inclusive 926 to 970, inclusive 971 to 1044, inclusive 1045 to 1095, inclusive 1096 to 1131, inclusive 1132 to 1186, inclusive 1187 to 1230, inclusive 1231 to 1287, inclusive 1288 to 1365, inclusive 1366 to 1440, inclusive 1441 to 1527, inclusive 1528 to 1581, inclusive 1582 to 1587, inclusive 1588 to 1595, inclusive 1596 to 1614, inclusive 1615 to 1624, inclusive 1625 to 1650, inclusive 1651 to 1660, inclusive 1661 to 1680, inclusive 1681 to 1688, inclusive 1689 to 1692, inclusive 1693 to 1699, inclusive 1700, 1701 and 1702 Week Ending May 15, 1976 May 22, 1976 May 29, 1976 June 5, 1976 June 12, 1976 June 19, 1976 June 26, 1976 July 3, 1976 July 10, 1976 July 17, 1976 July 24, 1976 July 31, 1976 August 7, 1976 August 14, 1976 August 21, 1976 August 28, 1976 September 4, 1976 September 11, 1976 September 18, 1976 September 25, 1976 October 2, 1976 October 9, 1976 October 16, 1976 October 23, 1976 October 30, 1976 November 6, 1976 November 13, 1976 November 27, 1976 December 4, 1976 December 11, 1976 December 18, 1976 December 25, 1976 January 1, 1977 January 15, 1977 January 22, 1977 January 24, 1977 (Date of last test) Certain lots on La Costa Vale Unit No. 3 were not graded during this period. Those lots not graded v/ere Nos. 428 to 440, inclusive, 457 to 468, inclusive, 472 to 481, inclusive, 485 and 486. 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 except in certain street areas which will be recompacted at a future date. It has been determined that the fill materials, compacted to 90 percent BENTON ENGINEERING, INC. Project No. 74-5-2D -3- February 4, 1977 La Costa Vale Unit Nos. 3 and 4 of the maximum dry density, have a safe bearing value of 1800 pounds per square foot for one foot wide continuous footings founded at the minimum required 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 5 feet inside the top of compacted filled ground slopes, these should be deepened one foot below a 1 1/2 horizontal to 1 vertical line projected outward and downward from a point 5 feet horizontally inside the top of compacted filled ground slopes in areas of no rock disposal.* Footings founded at least one foot below the surface of the firm undisturbed natural soils may be designed using an allowable bearing value of 2000 pounds per square foot. "Expansive" soil conditions exist within the upper three feet below finished grade on certain lots. The classification of each lot with regard to "expansive1' soil conditions is presented as follows: Type "A" (Critically Expansive) La Costa Vale Unit No. 3 - Lors 406 to 410, inclusive 412, 415 487 to 492, inclusive La Costa Vale Unit No. 4 - None lype "B'^J^harginally Expansive) La Costa Vale Unit No. 3 - Lots 416, 417 _ 469, 470, 471 482, 483 and 484 La Costa Vale Unit No. 4 - Lors/47s, 48 73, 74 90 t-n TQ?f inclusive 1JJ8 to III, inclusive" Type "C" (Nonexpansive) La Costa Vale Unit Nc^S - Lots 296 to 405, inclusive 411, 413, 414 418 to 427, inclusive 441 to 456, inclusive La Costa Vale Unit No. 4 - Lots 1 to 46, inclusive 49 to 71, inclusive 75 to 89, inclusive 103 to 107, inclusive 1 12 to 114, inclusive * In areas where rock disposal was made at the rear of certain lots as shown on the attached Drawing Nos. 1 T 2, and 3, no footings should be placed closei to the top of slopes than 5 feet horizontally inside of the approved compacted filled ground limits shown by dashed lines. BENTON ENGINEERING. INC. Project No. 74-5-2D -4- February 4, 1977 La Costa Vale Unit Nos. 3 and 4 Lots Not Graded an La Costa Vale Unit No. 3 - Lots 42ofTb 440, inclusive 457 to 468, inclusive 472 to 481, inclusive 485 and 486 La Costa Vale Unit No. 4 - None These lots that have not been graded should be classified at the time of construction. In order to minimize possible detrimental effects caused by the I;expansive" soil conditions on the proposed residential lots, the following special design and precautions are recommended: Type :|A" (Critically Expansive) 1 . Use continuous interconnected reinforced concrete footings, wherever possible, and place these at a minimum depth of 2.0 feet below the lowest adjacent exterior final ground surface. If isolated interior column footings are required, these should be placed at a depth of 2.5 feet belov- the lowest adjacent ground surface. If in-place rock conditions are encoun- tered at depths of less than 2.0 feet, then lesser depths of excavation are permissible to a minimum of 1 .0 foot. 2. Reinforce and interconnect continuously with steel bars all interior and exterior footings with a minimum of one "5 bar at 3 inches above the bottom of all footings and one ^5 bar placed 1 1/2 inches below the top of the stems of the footings. 3. Reinforce all concrete slabs with a minimum of 6x6 - 1 0/1 0 welded wire fabric and provide a base layer of at least 4 inches of 3/4 to 1 inch size crushed rock beneath all concrete slabs. A moisture barrier should be provided above the crushed rock and then 2 inches of sand should be placed over the moisture barrier and below the bottom of the slab. 4. Separate garage slabs from perimeter footings by a 1/2 inch thickness of construc- tion felt or equivalent, to allow independent movement of garage slabs relative to perimeter footings. Assure complete separation by extending the felt over the full depth of the front thickened edge of the garage slab. Also, cut off the garage door stops at least 1/2 inch above the slab. 5. Provide positive drainage away from all perimeter footings with a vertical tall of at least 5 inches in a horizontal distance of 5 feet outside the perimeter of the house. 6. Exercise every effort to assure that the soil under the foundations and slabs has a uniform moisture content 1 percent to 3 percent greater than optirr jr through- * The required design for commercial buildings may differ from the recommendations presented herein. BENTON ENGINEERING, INC. Project No. 74-5-2D La Costa Vale Unit Nos. 3 and 4 -5-February 4, 1977 6. Cont. out the top 3 feet below finished grade at the time of placing foundations and slabs. The moistened soil conditions need not extend to a depth of 3,0 feet in those areas where rock or very firm nonexpansive soil conditions are encountered at depths of less than 3.0 feet. Type ''B" (Marginally Expansive) Use the same design as recommended for Type "A" lots except items 1 and 2 should be modified as follows: 1. The continuous footings may be placed at a minimum depth of 1.5 feet below the lowest adjacent exterior final ground surface. 2. Single ^4 bars, placed as directed above, may be substituted for the ^5 bars recommended for the Type "A" lots. Type "C " (Nonexpansive) Special design for expansive soil conditions will not be required for lots classified in this category. Oversized rock v/ere buried in certain designated areas in accordance with the project specifications, The approximate locations of these rock disposal areas are shown on the attached Drawing Nos. 1, 2 and 3. It is possible that natural in-place rock formations or large rock fragments may be encountered in excavating to depths of greater than 1 .5 feet below finished grade in certain areas. All buried exterior utility lines should be City of Carlsbad approved plastic lines due to the corrosive characteristics of the soils, unless sufficient field tests are taken to establish that noncorrosive soils exist in the utility trench areas. Two tests taken in street subgrade and areas of trench backfill that have been placed at less than the required degree of compaction will be recompacted at a future date. These tests are noted ':To be Reworked" in the remarks column of the "Table of Test Results." Respectfully submitted, BENTON ENGINEERING, INC By ,~ r, (2) (1) Attention: Mr. Burton C. Kramer (2) City of Carlsbad, Eng. Depart. (1) Rick Engineering Company, Carlsbad (l,i YVarmington Development, Inc. Attention: Mr. Bart Pitts _ Philip H. §enton, Civil Engineer R.C.E. No. 10332 BENTON ENGINEERING, INC. |A AliuMC.3^ 8£NTON ENGINEERING MECHANICAL ANALYSIS CF SOILS Project ',/ <"•*-> £-r A /x*^ ' cT '»«' * J -i*"*f *•> >«*** ,_». >.. .""»No. / ^ - o - *., ,o -- Hole No. Sample No. /?/* , , -f . \" /. / t? r- "h" Depth Date 5*' Z.S'- "7 7 Testwd Bv -' . '' ( - • Checked By ANALYSIS of MATERIAL Retained On Sieve (W|) ANALYSIS of MATERIAL From Hydrometer Analysis Sleva No. ['<- i **~ '> 1U7& Pcsn Total Wgt. Retained iii . \& <66itf ^9 tsot'o 13 t; -7 /?J 5 | Cum. Wgt. Passing t | ^Tb!r> s?3,; ^-« I*.? * i i ! i Cum. % of Total Passing >^ / /oa-6> >; 3 3 . <1- * *7 . ^ ^ Sieve No. Pan Total Wgt. Retai ned Cum. Wgt. Pass ing Cum. % of Total Passing Hydrometer Analysis Wgt. Mate Clock Time Time Min. 1 2 5 10 15 30 120 250 1440 Temp.Hydro. Read i ng Corrected Read ing Partial 0 1 am . mm -i al q . Percent of ^2 F iner than D ' W2 Percent of Total Sample Wj W2 ... i ZZ33708 BENTON ENGINEERING MECHANICAL ANALYSIS OF SOILS Project JL.A ^/^c7 //u/TTT I? .T- 4-Data Hole No.Sample No. Tested By .F) [? Depth Checked By ANALYSIS of MATERIAL Retained On Sieve (W|) ANALYSIS of MATERIAL From Hydrometer Analysis Sieve No. / ^• -%^ \ A- r'^- "~.t>'€> Pan Total Wgt. Retaji ned i ,o .t> 5^ 1 i o *j -7 1 3 L * ^ 4o T C^o. fc> I7- -7. ^ ^2. £ ^ \ Cum. Wgt. Passing t?rojo n .^, 3 &3 \O 1^, C Cum. % of Total Passing i v 1 00.10 x TS14- V 7^J?iZ x- ^ ; <5 x Sieve No. Pan Total Wgt. Retained Cum. Wgt. Passing Cum. % of Total Passing Hydrometer Analysis Wgt. Material 9 - Clock Time Time Min. 1 2 5 10 15 30 120 250 1440 Temp.Hydro. Read i ng Corrected Read i ng Partial 0 i am . mm Percent of W2 F iner than D Percent of Total Sample Wj W2 ZZ33708 BENTON ENGINEERING MECHANICAL ANALYSIS OF SOILS Project ,/,A c-o 5~~X, No. 7^-- S - ^ 0 F :? r—4-Date Tested By Hole No.Sample No./s I/ ^Depth Checked By ANALYSIS of MATERIAL Retained On Sieve (W|) ANALYSIS of MATERIAL From Hydrometer Analysis S ieve No. /^ / <4- -fr? 2^0 Pan Total Wgt. Retd i ned i j .& m.iS- s°& 11 1 13 4{ (?* ii i Cum. Wgt. Passing 2150. 10. -c? r 1 £~J 4- 1i i i i Cum. % of Total Passing K < -J ^ ^r/ O€> O K 7 o ! 7 X.u> ** , C» v ^JL A t i Sieve No. Pan Total Wgt. Retai ned ! 2.STo.^> lo^'^J OifcJ *--' '* i Hydrometer Analysis ; Wgt. Mate Clock Time Time Min. ; 1 2 5 10 15 30 120 250 1440 Temp.Hydro. Read i ng Corrected Read i ng Part i a 1 Dlam. mm Cum. Wgt. Passing -ial q « Percent of W2 F iner than D Cum. % of Total Passing w2 Percent of Total Sample Wj W2 ZZ33788 BENTON ENGINEERING MECHANICAL ANALYSIS OF SOILS Project jLA. co-r^A No. -74-- 5" -•*, OF of- -T-Date Hole No.Sample No. j5 S4-Depth Tested By _ Checked By_ ANALYSIS of MATERIAL Retained On Sieve (W|) ANALYSIS of MATERIAL From Hydrometer Analysis S leva No. t^ I ~J~ _"C? ~Z>rSO Pesn Total Wgt. Retained i I \0 /6/ii? si'--!*. •z. s^o.S o i n j o 3 *\& ! Cum. Wgt. Passing ; 1 D O/O p V/- t-- .t?/. D Cum. ^ of Total Passing I K 1 x mo- O x: 15*1 4- K ]2;4 x s t 1 ii Sieve No. Pan Total Wgt. Retained Cum. Wgt. Passing Cum. % of Total Passing ; Hydrometer Analysis Wgt. Mate Clock Time Time Min. 1 2 5 10 15 30 120 250 1440 Temp.Hydro. Reading Corrected Read i ng Partial 0 i am . mm -ial q . Percent of W2 Finer than D W2 Percent of Total Sample Wj W2 ZZ33708