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04790 (SFD) Geotechnical InvestigationLEIGHTON AND ASSOCIATES, INC. Geotechnical and Environmental Engineering Consultants GEOTECHNICAL INVESTIGATION PROPOSED SINGLE-FAMILY RESIDENCE 3/4 -ACRE SITE ON SOUTH SIDE OF COACHELLA DRIVE ASSESSOR'S PARCEL #617-680-005-5 LA QUINTA COUNTRY CLUB LA QUINTA, CALIFORNIA July 21, 1988 . Project No. 5880127-01 Prepared for: THE HAYES COMPANY 3186D Airway Avenue Costa Mesa, California 92626 Attention: Mr. Dan Hayes 7A-240 HIGHWAY 111, PALM DESERT, CALIFORNIA 92260 (619) 568-0993 FAX (619) 341-7490 TO: ATTENTION: SUBJECT: Introduction LEIGHTON AND ASSOCIATES, INC. Geotechnical and Environmental Engineering Consultants July 21, 1988 Project No. 5880127-01 The Hayes Company 3186D Airway Avenue Costa Mesa, California 92626 Mr. Dan Hayes Geotechnical Investigation, Proposed Single -Family Residence, 3/4 -Acre Site on South Side of Coachella Drive, Assessor's Parcel #617-680-005-5, La Quinta Country Club, La Quinta, California In accordance with your authorization we have conducted a geotechnical investiga- tion at the subject site. The scope of our work included (1) site reconnaissance; (2) excavation, logging, sampling and backfill of three exploratory trenches up to 15 feet in depth; (3) laboratory testing of geotechnical properties of repre- sentative soil samples; (4) geotechnical analysis of field and laboratory test data and (5) preparation of this report presenting our findings, conclusions and recommendations. Our present scope of work did not include any assessment of the possible presence of hazardous chemical materials at the site. The approximate location of the exploratory trenches is shown on the drawing titled "Location of Trenches". A topographic survey map, provided by The Hayes Company, dated November 30, 1985 was used as a base map for this investigation. Accompanying Maps and Appendices Site Location Map - Page 2 Figure 1 - Location of Trenches - Rear of Text Appendix A - Sampling and Testing Procedures Appendix B - Geotechnical Trench Logs Appendix C - Laboratory Test Results Appendix D - General Earthwork and Grading Specifications Appendix E - References 74-240 HIGHWAY 111, PALM DESERT, CALIFORNIA 92260 (619) 568-0993 FAX (619) 341-7490 lC ` ,\�J so�.l• � /.'; t,y�' �,�/�)r;%%�; ` .....: �- - y�rJl eye' .. � .. .... 'C Trader � �� v\\�:�.w✓11 ;p; ll `(,(fi r.r, 1. ( _vim' - : ' �^.\y • �!/� o. .. _^ 1 � ; of ml Welt.ta .... •........ tu Q 3I $'2 .0 (� /_ _ moi.' r :• • ..._.',.. - r\5 , . �.. 4t/ ,. Water 0.. 14 n G O • Water• _ .',Water W ell IF y 30 II r U \ ' L If ' �J Well o u I a if if n •1 I II W 2 : 0 a a n u 3 O /^/ u U "O �n If We ' L 40 Q _Q_ ;, �,�. W V Q � as n==o===ec u II • jfr✓ ��;'.. .II _===--D ____--- Water i•pV :,. :I •�. �� .:. Ifs u -. r •I:==� FY! -E! J fix%_ BASE MAP: USGS 7-1/2' QUADRANGLE "LA QUINTA, CALIFORNIA", Photorevised 1980 2000 4000 scale feet 2K, 2 —I PROPOSED SINGLE FAKILY RESIDENCE, 3/4 ACRE S[TE LOCATED ON SOUTH SIDE OF COACHEL'LA DRIVE ASSESSOR'S PARCEL #61.7'-680-005 LA QUINTA COUNTRY CLUB LA QU[NTA, CALIFORNIA SITE LOCATION MAP n • Project No. 5880127_01 LEIGHTON and ASSOCIATES INCORPORATED 2 - All 5880127-01 SITE CONDITIONS AND PROPOSED DEVELOPMENT Site Conditions The site is bordered on the north, south and west by the La Quinta Country Club golf course, and to the northeast and east by Coachella Drive. At the time of our field investigation, the site appeared to have been rough graded and had minor amounts of asphalt chunks, trash and debris scattered along the southeastern property line. Soils exposed at the ground surface consisted of fine grained silty sand. Several stockpiles of sand used for the golf course sand traps were on the surface in the middle of the site. W Proposed Development It is our understanding that the subject site will be developed to support a one-story single family residence of wood frame construction with interior parking area. No site grading plans were available at the time of the report, however, the final grades of the building pad are expected to be founded near the existing grades with slab -on -grade floors and light foundation loads. " FIELD AND LABORATORY INVESTIGATIONS Subsurface Investigation The subsurface soils at the site were examined by means of three backhoe trenches excavated to depths of 15 feet. The trenches were continously logged by our field engineer, who collected representative samples of the soils encountered for fur- ther classification and testing. Sampling procedures are described in Appendix A. Approximate locations of the trenches are shown on Figure 1. Summaries of the trench logs are presented in Appendix B. Laboratory Testing Samples of soils obtained from the exploratory trenches were returned to our laboratory for further testing. The in-place moisture content and density of the soils are presented in the trench logs of Appendix B. Maximum density and grada- tion testing was performed on representative samples and the results are presented in Appendix C. YIN 3� -3- LEIGHTON AND ASSOCIATES A - 5880127-01 SUMMARY OF GEOTECHNICAL CONDITIONS Earth Materials The earth materials encountered during our site investigation consisted of al- luvial and lacustrine (lake deposits from the ancient Lake Coahuila) soils, mainly silty sand, sandy silt and some clayey silt and sandy clay. In general, the soils in this area were brown to light gray in color, slightly moist, and medium dense. Sieve analysis of four samples indicated from 18 to 87 percent of the soil frac- tion passing the #200 sieve. Based on the results of the Atterberg limits test, some of the onsite natural soils appear to be moderately expansive. Ground Water No free ground water or seepage was encountered in any of the trenches during our investigation. Based on information received from the Coachella Valley Water District, the regional ground water levels in the vicinity should be on the order of 95 feet or more below the ground surface. This water level may be expected to vary seasonally, but is not expected to impact construction at the site. Seismicity Regional geologic maps show that the nearest known active or potentially active faults to the site are the Mission Creek Fault and the Banning Fault, branches of the San Andreas Fault zone. These faults both trend northwest -southeast in the site area. The Banning Fault approaches within about 7 miles of the site and the Mission Creek Fault approaches within 8 miles of the site. Regional geologic and fault hazard maps show no faulting to be present at the site. The site is not included in the California Special Studies Zone. Liquefaction, a phenomenum involving total or substantial loss of shear strength in saturated soil, is caused by the buildup of excess hydrostatic pressure in saturated cohesionless soils as a result of cyclic stresses generated by ground motions. The Riverside County Seismicity and Safety Element (1976) indicates 'the liquefaction potential at the site is minimal. Our investigation generally con- firms this finding due to the great depth to free ground water at the site. �F•'jy�. ri 4-S-s-,� LEIGHTON AND ASSOCIATES 5880127-01 CONCLUSIONS AND RECOMMENDATIONS Conclusions Based on the results of our field exploration, laboratory testing and our ex- perience and judgement, in -our opinion the site is suitable for the proposed development from a geotechnical standpoint. Conventional spread footings should provide adequate support for the proposed structure with tolerable settlements. Some overexcavation, scarification, presoaking, and reworking of soils as com- pacted fill is recommended for areas to support structures or pavements to provide uniform foundation conditions, adequate bearing capacity and to minimize settle- ment. Because of the expansive nature•of some of the on-site soils, certain measures should be taken to reduce the potential for expansion and heaving of the foundation soils. Further testing during construction may be performed to better evaluate the nature and extent of potentially expansive soils at the site. . Due to the low confining pressures imposed by slabs -on -grade, they are particularly susceptible to damage by expansive soils. Treatment or removal of clayey soils encountered in the building area will be required to reduce the expansion poten- tial. The clayey onsite soils should be removed from all pavement or structure areas to a depth of at least 24 inches below the finished grade elevations, and replaced with non -expansive, granular fill materials. Alternatives to this procedure include stabilization of the soils with lime or soaking the subgrade soils to induce their expansion before the concrete pour. Recommendations 1. Site Preparation All grading should be performed in accordance with our General Earthwork Grading Specifications (Appendix D) except as modified in the text of this report. The site should be stripped of any trash, debris, vegetation, roots, undocu- mented fill soils and soft soils up to the required depth. During rough grading, excess soils may be stockpiled for later use. Soils containing more than one percent by weight of organics may be used in planter areas, but should not be used for fill beneath building and paved areas. Debris and trash, plus any rocks or rubble over 6 inches in size should be removed from the site. After clearing, clayey soils should be removed to a minimum depth of 24 inches from existing ground or finish grade elevations, whichever is deeper. The exposed excavations should be further scarified, moisture condi- tioned to optimum moisture and recompacted to a minimum of 90 percent relative compaction to a depth of 6 inches prior to placement of non - expansive granular fills. Additional excavation will be required in any areas to support structures or pavements where soft or loose soils are encountered. The excavation should extend a minimum of 5 feet beyond the building footing lines. The imported fill soils to be used at the site should be sampled and approved by the soil engineer prior to placement as compacted fill. 5 LEIGHTON AND ASSOCIATES ,.� 5880127-01 The trenches excavated for our subsurface exploration were up to 15 feet deep, approximately 15 feet long, and 3 feet wide. After logging and sam- pling, they were loosely backfilled. Where structures or pavements are planned at these locations, the trenches should be re -excavated to a depth of at least 36 inches below existing grade, as described above, scarified, heavily watered, recompacted, and backfilled with properly controlled com- pacted fill. 2. Compacted Fill The onsite sandy soils, free of organic material, are suitable for "use as compacted fill. The onsite clayey soils should be disposed of or used in non-structural areas. Alternatively, these soils could be blended. Import materials should be tested and approved prior to use as fill at the site. Import should conform to the specifications in Appendix D. Any fill soils used should be moisture conditioned to near optimum moisture content and compacted to at last 90 percent relative compaction in accordance with ASTM D1557-78. Fill should generally be placed in uniform lifts not exceeding 8 inches (loose). 3. Shrinkage and Subsidence Based on test results, scarification and recompaction of the upper foundation soils should result in a shrinkage on the order of approximately 15 percent. This is based on an estimated average relative compaction of 92 percent. An increase in relative compaction obtained will correspondingly increase this shrinkage factor. A subsidence (due to equipment operations and prewatering) of approximately 0.25 feet is typically assumed in areas of desert soils such as those at the subject site. Additional volume loss may occur due to ex- cavation of clayey soils from the subgrades at the site. 4. Foundation Design - Footings After site preparation as recommended, the use of shallow continuous footings or isolated spread footings is feasible. The footings for one-story or two- story structures should be 15 inches deep and at least 12 inches wide. A maximum allowable bearing value of 1800 psf is recommended for footings constructed in this manner. This value may be increased by one-third for wind or seismic loads. The footings may be reinforced with at least one No. 4 bar at the top and bottom to reduce the potential for cracking due to temperature and shrinkage stresses. All footing excavations should be kept moist by sprinkling until the time of the concrete pour. Adverse amounts of settlement foundations become wetted after minimize the infiltration of drainage should be provided to slabs. or expansion may occur if the soils below the construction. It is therefore important to water into the foundation soils. Positive direct surface water away from structures and IME 5880127-01 Resistance to lateral loads can be developed by frictional resistance on the footing bottoms and passive pressure against footing sides. The frictional resistance can be computed using a frictional coefficient of 0.3. An allow- able lateral bearing value of 200 pounds per square foot per foot of depth may be used in calculating the resistance of dense natural soils or properly compacted fill to lateral forces. Passive pressure should be neglected when computing lateral resistance unless the area adjacent to the foundations is confined by a slab or pavement. 5. Surface Drainage and Lot Maintenance No water should be allowed to pond adjacent to the residence. Positive drainage may be accomplished by providing drainage away from the building at a gradient of at least 2 percent for a distance of at least 5 feet, and further maintained by a swale or drainage path at a gradient of at least 1 percent. Where necessary, drainage paths may be shortened by use of area drains and collector pipes. We suggest the installation of eave gutters and downspouts on the building, which will facilitate roof runoff away from the foundations. The discharged water from the downspouts should be directed away from the building to an appropriate outlet. Some routine site maintenance should be expected to be required at intervals during the life of the structure. This may include maintaining grades to drain away from the structure, restoring soil removed from foundation areas by animal activity, wind or water erosion, etc. 6. Concrete The slab subgrade and footing excavations should be properly moistened prior to placing of concrete. Concrete with low water:cement ratios and low slump (preferably 4 inches) when properly placed, vibrated, and cured will have a low potential for shrinkage cracking. 7. Slabs -on -Grade Slabs -on -grade should be at least 4 inches thick and should be reinforced in accordance with local codes and structural considerations. We suggest that slabs -on -grade be reinforced by either wire mesh (6 x 6 - 10/10 WWF) or #3 rebars at midheight in the slabs, spaced 18 inches on center in both direc- tions. We recommend that a moisture barrier consisting of a 6 -mil polyethylene sheet be placed beneath slabs in areas sensitive to moisture damage. The moisture barrier should have a 2 -inch layer of clean sand placed above it to aid in concrete curing. Openings in the vapor barrier should be carefully sealed and the vapor barrier should be carefully installed to avoid puncturing it and reducing its effectiveness. MM 5880127-01 8. Asphaltic Concrete Pavement Based on the classification, we expect the R -value of the onsite soils to be on the order of about 25 or more. Considering -this, a tentative structural pavement section consisting of 5.5 inches AC over compacted subgrade soils or 2.0 inches AC over 6.5 inches crushed aggregate base should satisfy an as - fm sumed traffic index of. 4. This traffic index is generally assumed for pavement design of parking stalls and light service conditions. The upper 12 inches of subgrade materials below pavements should be compacted to 95 per- im relative compaction. Asphaltic concrete should conform to Section 203 of the most recent edition of "Standard Specifications for Public Works Construction," (SSPWC). Base course should be a Crushed Aggregate Base or Processed Miscellaneous Base conforming with Sections 200-2.2 and 200-2.4 of the SSPWC. The base course and AC should be placed in accordance with Sections 301-2 and 302-5 of the SSPWC. Our pavement evaluation was based on assumed traffic indices and the physical properties of the near -surface soils encountered on the project site. These recommendations should be reviewed if import soils are placed -in the pavement areas or if the site conditions during construction appear to the different from those indicated by our borings. If the traffic index values vary from the values given or import soils are placed in pavement subgrades, then this office should be notified so that pavement sections can be revised accord- ingly. 9. Seismic Considerations Seismic design considerations for structures in the southern California area are critical because of high regional seismic activity. Seismic design should be in accordance with the provisions of the current Uniform Building Code and the seismic design parameters of the Structural Engineers Association of California. 10. Temoorary Construction Excavations The onsite soils are subject to caving. Particular attention should be given to the possibility of caving along trench excavations. Laying back or shor- ing of deep utility excavations should, therefore, be a consideration. Temporary excavations during construction should be designed in accordance with the applicable safety codes. Sandy soils exposed in temporary construc- tion excavations should be kept moist but not saturated to retard ravelling and sloughing during construction. IN 5880127-01 11. Observation and Testing During Construction The recommendations provided in this report are based on preliminary design information and subsurface conditions obtained from the exploratory trenches at the site. Geotechnical observations and testing during construction are the continuation of this geotechnical investigation and not separate unique functions. Field review during site grading allows for evaluation of the exposed soil conditions and. confirmation or revision of the assumptions and extrapolations made in formulating the design parameters and recommendations. If an engineering firm other than Leighton and Associates is contracted to act as soil engineer during later phases of this project, they should notify the owner, project designers, the appropriate regulatory agencies, and this office that they have assumed responsibility for all phases (design and construction) of the project within the purview of the geotechnical engineer. Notification should indicate they have reviewed this report and any 'sub- sequent addenda and either agree with the conclusions and recommendations or will provide new recommendations. Final project drawings should be reviewed by the geotechnical engineer prior to grading to see that the recommendations provided in this report are incorporated in the project plan. Construction should be observed by the geotechnical engineer at the following stages: • Upon completion of clearing and during excavation of building and pavement areas. • During all stages of grading and earthwork operations including scarifica- tion, recompaction, and while utility trench backfilling. t Prior to paving or other construction over fill or backfill. • When any unusual soil conditions are encountered during construction. A final report should be prepared upon completion of the construction, sum- marizing the compliance with the recommendations of this report and geotechnical observations during the grading work. If conditions during construction appear to be different from those indicated in this report, this office should be notified. A LEIGHTONAND ASSOCIATES z 5880127-01 If you have any questions regarding our report, please do not hesitate to contact this office. We appreciate this opportunity to be of service. Respectfully submitted, OFESSIj LEIGHTON AND ASSOCIATES, INC. ti INGHP M NGHP�AM � ' a: 4+ No. 40264 ,,, Douglas E. Stephenson Staff Engineer CiVIL lFOF CAtIBrent J. Inghram, RCE 40264 fan Chief Engineer —123 DES/BJI/mu Distribution: (6) Addressee - 10 - MA 5880127-01 APPENDIX A SAMPLING AND TEST PROCEDURES Sampling Procedures Backhoe Trenches: Bulk samples were obtained from the trenches and returned tc our laboratory for testing. In-place density and moisture tests were performed at various depths in the trenches as well as selected locations outside the trenches on the existing ground surface. In-place densities and moisture contents were determined in accordance with the sand cone method, ASTM D1556 and/or nuclear densometer method, ASTM D2922. The exploratory trenches were logged by our field representative concurrent with their excavation. Representative samples were bagged and transported to our laboratory for testing. Laboratory Testing Procedures Classification Tests: Typical materials were subjected to mechanical grain -size analysis by wet sieving with U. S. Standard brass screens. The data was used to evaluate the classification of the materials. A graphical presentation of the grain -size distribution is presented in the test data and the Unified Soil Classification is presented in both the test data and the Trench Logs. Maximum Density Tests: The maximum dry density and optimum moisture content of typical materials were determined in accordance with ASTM D1557-78. MAJOR DIVISIONS I S`."FOES TYPICAL NAMES GSI `:P •�l' Well nraded gravels or gravel -sand mixtures, little or no fines u C' •C� N GRAVELS GP • :0.: �, Poorly graded gravels or gravel -sand mixtures, little oro fines N > J N O 'N (More than 1/2 of G[4 Silty gravels, gravel -sand -silt mixtures N N O , W coarse fraction ) I o i Q 2 C no. 4 sieve size) GC •'' Clayey gravels, gravel -sand -clay mixtures Q oC 0 u a S14 : ..�. Well graded sands or gravelly Sands, little or no fines W N N c SANDS ' o .. ' ,$p Poorly graded sands or gravelly sands, little or no fines V C A (More than 1/2 of SM Silty sands, sand -silt mixtures d 0 coarse fraction < "t 6,11 no. 4 sieve size) SC Clayey sands, sand -clay mixtures d ML Inorganic silts and very fine sands, rack flour, silty or is clayey fine sands or clayey silts with slight plasticity ' N N O SILTS CLAYS CL Inorganic clays of low to medium plasticity, gravelly clays.sandy J N clays, silty clays, lean clays o c N � LL<50 �,,•�,: O OL Organic silts and organic silty clays of low olasticity W % I li�I 0 a .,N, Mlt HInorganic silts. micaceous or diatomaceous fine sAndy or u o SILTS 8 CLAYS silty soils. elastic silts W C v CH Inorganic clays of high plasticity, fat clays LL > 50 01j ';;/'/� Organic clays of medium to high plasticity, organic silty clays, organic silts Is (HIGHLY ORGANIC SOILS (pl � Peat and other highly organic Soils I CLASSIFICATION CHART (Unified Soil Classification System) 60 CLASSIFICATION RANGE OF GnAiPI SIZES I U. S. Standard Grain Size in 50 W Sieve Size Millimeters vMENE 40 >nji ABOVE 12" I BOULDERS000 30 ABOVE 305I MEMO o- N 20 COBBLES- 12" To 3" 1305 To 76.2 C6 wjwmi i to � GRAVEL 3" To P;o. 4 4 7E,2 To 4.761 o -- COARSE Y. to 3/4" 76.2 to 19. t 0 10 20 30 40 50 60 70 Co 50 100 FINE 3/4" to Mo.4 19,1 to 4.76 LIQUID LIMIT SAND No.4 To 200 4,7G TOO. 074 PLASTICITY CHART COARSE No.4 to 10 4.76 to 2.30 MED I UM No. 10 to 40 2.00 to 0.420 FINE No. 40 to 200 0.420 to 0.074 SILT 8 CLAY BELOu N0. 420 I BELOW 0.074 GRAIN SIZE CHART METHOD OF SOIL CLASSIFICATION GEOTECHNICAL TRENCH LOG Trench No, T-1 ?roject ay La Quina pment Co. V� Ile ac�Ci►oe 'levation + Bio n� (T ���,.,r,I Survev Sheet . I Qf I_ Job No. 52801)7-0 Type of Equip.Forj 555 pau�oe • Z y.. 4J 'Ln- N C7 • N rO N GEOTECHNICAL DESCRIPTION 'a r m 5 C n. � 4j eta' a) n. M a 3 -r-' c U U • -:- : Logged By DES . cn O N ~ -11 o cn = Sampled By 'DES - Silty Sd : An te'},sli wy Moi +' li:36 smy, root s e+s in Sad FSM Uayay Stlt ; Mediums s+i#,-0is+, br ", 9" +click layer 94.9 3. SawJy cbr/Sil4ySmA : Fine gnaineJ,meclium dense,sli9irtly Iiois}j gray 94.G 4.1 58% Passing #a00sieve 1 5 SM 5;1 SanJ :Pin naineJ, melum Jense, sli 6 moil+, li 4 �_ 9 9 � 9 9^ay Bo+4bn� TmnA a+ 15` DeP+L ' No �me GrwviJ "ler Encoun-leyeoi Trenc, Sacktilled r � GEOTECHNICAL TRENCH LOG Trench No. T Sheet f 'ect _I-i(A es La Qui„+� Job No. 58S01a?-0I w1,1 pment Co. Uallev Back�o Type of Equip.Fo.d 57c 5 $ackLoe �levation + 500' iTeoe4r+ao�+ic Survev� • y-. +� N 34 C7 • N �C N GEOTECHNICAL DESCRIPTION A�U-m Q- ~ 4- uH� a +j QJ -o Cn Logged By DES � a � � � 0 0 I Sampled By DES SM Sit Sand . Fiwe jensefslijWy rneistj N94 3MY, groinej,r„ejiun, Foss roo+lets +a GO Je f � 3a,y ML Clgyoy Sil+. Medius, s^very .ois.+ 6roam,-iA minorfine W, 1 -4 Minor Pore S"r-4ure 8776 ssin *';L00sieve- SM si Sand: Fine 9minod, VAecliun, deAse)wois+, li94+ gray 5 Na% passing *- oW sieve 15 . Bo++ow, oTr Tre„cL at 15' Deft► II No Free Ground Wa+er Encounfiered TrencL eacKilej t GEOTECHNICALTRENCH LOG Trench No. - Sheet _If I___ Project Na La Ou;nia pment Co. ,. R2A l eva ti on i9.0�M JfY_f�L[_ S.,yti/ Job No. 58801x7-01 Type of Equip. Ford SGS &,"*e • 2 a2 H C; .� c M N GEOTECHNICAL DESCRIPTION d7 - r N d D 4- +; 7 c +� Q1 U U • MW a ca m s E ;00 >;� a -� c T v= Logged By DES �, . ; N '- o N = Sampl ed By DES SM Si�: Fi„e smihed,Meciia►dense,�ery sli9irilr rnas+, liy{ri 9my i 9►'z motlets -to V, dePA t1L SM «ate s;>+:M.a,wM •�1iF�,neis+,�«�,, s••+�►.� lays• 89.5 5.9 Si SoMv : Fine gmmd, mediwwl Jesse, Moist, li9h+• gray IN99.4 9.7 1870 passing #•200 sieve 1 5 I . Bo+ vm k Tmncl at 15' Depth No Free. Ground - Wa+er Encountered Trenc,� $aCktilled 5880127-01 MAXIMUM DENSITY TEST RESULTS * Sample Location Soil Description T-3, Bulk -1 @ 4-5' Silty Sand: Fine grained, light gray * In accordance with ASTM D1557-78 Optimum Maximum Dry Moisture % Density (pcf ) 15.5 105.0 C -i wM Y � U.S. Standard Sieves U:S. Standard Sieve Numbers Microns f — in inches —I �— r— Q .3 0 .90 D U) 0 0 vn C:) 00 o_ N v 0 is 0 Z 0 60 10 5 1 0.5 0.1 0.05 0.01 0.005 0.001 Grain Size in Millimeters Gravel Sand Course ' Fln• Coors• Medium Fin• Silt Clay LSymbol Hole No. Sample No. Depth or Elev. Field Moisture (° ) LL (°� ) ° PI (o� ) ° Activity PI/ 2u Cu eo/o ° to Cc (D30)2 lob jOso Percent Passing No. 200 Percent Passing 2u U.S.C.S. T I Bulk -I y'S' — — — — — — 58 — ML T-) Bulk -i a�3' -- — — — — — g7 — ML GRADATION TEST RESULTS 7 U.S. Standard Sieves U.S. Standard Sieve Numbers Microns I - in inches 1 F-- 10 5 1 0.5 0.1 0.05 0.01 0.005 Grain Size in Millimeters Gravel I Sand -Fine Coors* Medium Fine Silt Clay Symbol Hole No. Sample No. Depth or Elev. Field o Moisture ( ) LL (%) PI (%) Activity PI/ -2u Cu 060/0 ioipb Cc (Dso)2 •o60 Percent Passing No. 200 Percent Passing 2u U.S.C.S. T a Bulk -a 4=5r — — — — — — ya -- SM :0 T-3 Bulk -I y'S" — — -- — — 18 — SM GRADATION TEST RESULTS t 100 90 80 70 601 01 401 mi 19 •e i SAMPLE DEPTH FIELD SYMBOL HOLE NO. NO MOI %URE LL M PL M PI M O T-2 Bulk -1 2-3' ----- 52.0 23.0 29.0 50 X 40 a� c >1 30 V ,U R 20 CL FL 10 CH CL MH & OH CL—ML ML & OL U.S.C.S. CH 10 20 30 40 .: 50 60. 70 so'. 90- 10*0' LL (Liquid Limits), 96 ._.__._..._......_ _...... ATTERBERG LIMITS TEST RESULTS Project No. 5880127-01 Project Name Hayes, La Qui nta u Date 7/5/88 Figure No. C - iv 3005188 GENERAL EARTHWORK AND GRADING SPECIFICATIONS 1.0 General Intent These specifications present general procedures and requirements for grading and earthwork as shown on the approved grading plans, including preparation of areas to be filled, placement of fill, installation of subdrains, and excavations. The recommendations contained in the geotechnical report are a part of the earthwork and grading specifications and shall supersede the provi- sions contained hereinafter in the case of conflict. Evaluations performed by the consultant during the course of grading may result in new recommendations which could supersede these specifications or the recommendations of the geotechnical report. 2.0 Earthwork Observation and Testing Prior to the commencement of grading, a qualified geotechnical consultant (soils engineer and engineering geologist, and their representatives) shall be employed for the purpose of observing earthwork procedures and testing the fills for conformance with the recommendations of the geotechnical report and these specifications. It will be necessary that the consultant provide ade- quate testing and observation so that he may determine that the work was accomplished as specified. It shall be the responsibility of the contractor to assist the consultant and keep him apprised of work schedules and changes so that he may schedule his personnel accordingly. It shall be the sole responsibility of the contractor to provide adequate equipment and methods to accomplish the work in accordance with applicable grading codes or agency ordinances, these specifications and the approved grading plans. If, in the opinion of the consultant, unsatisfactory condi- tions, such as questionable soil, poor moisture condition, inadequate compaction, adverse weather, etc., are resulting in a quality of work less than required in these specifications, the consultant will be empowered to reject the work and recommend that construction be stopped until the conditions are rectified. Maximum dry density tests used to determine the degree of compaction will be performed in accordance with the American Society for Testing and Materials test method ASTM D1557-78. 3.0 Preparation of Areas to be Filled 3.1 Clearing and Grubbing: All brush, vegetation and debris shall be removed or piled and otherwise disposed of. 3.2 Processing: The existing ground which is determined to be satisfactory for support of fill shall be scarified to a minimum depth of 6 inches. Existing ground which is not satisfactory shall be overexcavated as specified in the following section. Scarification shall continue until the soils are broken down and free of large clay lumps or clods and until the working surface is reasonably uniform and free of uneven features which would inhibit uniform compaction. 3.3 Overexcavation: Soft, dry, spongy, highly fractured or otherwise un- suitable ground, extending to such a depth that surface processing cannot adequately improve the condition, shall be overexcavated down to firm ground, approved by the consultant. 3.4 Moisture Conditioning: Overexcavated and processed soils shall be watered, dried -back, blended, and/or mixed, as required to attain a uniform moisture content near optimum. 3.5 Recompaction: Overexcavated and processed soils which have been properly mixed and moisture -conditioned shall be recompacted to a minimum relative - compaction of 90 percent. 3.6 Benchin : Where fills are to be placed on ground with slopes steeper than 3.7 horizontal to vertical units), the ground shall be stepped or benched. The lowest bench shall be a minimum of 15 feet wide, shall be at least 2 feet deep, shall expose firm material, and shall be approved by the consultant. Other benches shall be excavated in firm material for a minimum width of 4 feet. Ground sloping flatter than 5:1 shall be benched or otherwise overexcavated when considered necessary by the consultant. 3.7 Approval: All areas to receive fill, including processed areas, removal areas and toe -of -fill benches shall be approved by the consultant prior to fill placement. 4.0 Fill Material 4.1 General: Material to be placed as fill shall be free of organic matter and other deleterious substances, and shall be approved by the consultant. Soils of poor gradati.on, expansion, or strength characteristics shall be placed in areas designated by the consultant or shall be mixed with other soils to serve as satisfactory fill material. 4.2 Oversize: Oversize material defined as rock, or other irreducible material with a maximum dimension greater than 12 inches, shall not be buried or placed in fills, unless the location, materials, and disposal methods are specifically approved by the consultant. Oversize disposal operations shall be such that nesting of oversize material does not occur, and such that the oversize material is completely surrounded by compacted or densified fill. Oversize material shall not be placed within 10 feet vertically of finish grade or within the range of future utilities or underground construction, unless specifically approved by the consultant. 4.3 Import: If importing of fill material is required for grading, the import material shall meet the requirements of Section 4.1. 5.0 Fill Placement and Compaction 5.1 Fill Lifts: Approved fill material shall be placed in areas prepared to receive fill in near -horizontal layers not exceeding 6 inches in compacted thickness. The consultant may approve thicker lifts if testing indicates the grading procedures are such that adequate compaction is being achieved with lifts of greater thickness. Each layer shall be spread evenly and shall be thoroughly mixed during spreading to attain uniformity of material.and moisture in each layer. 5.2 Fill Moisture: Fill layers at a moisture content less than optimum shall be watered and mixed, and wet fill layers shall be aerated by scarifica- tion or shall be blended with drier material. Moisture -conditioning and mixing of fill layers shall continue until the fill material is at a uniform moisture content at or near optimum. 5.3 Compaction of Fill: After each layer has been evenly spread, moisture conditioned, and mixed, it shall be uniformly compacted to not less than 90 percent of maximum dry density. Compaction equipment shall be ade- quately sized and shall be either specifically designed for soil compaction or of proven reliability, to efficiently achieve the specified degree of compaction. 5.4 Fill Slopes: Compacting of slopes shall be accomplished, in addition to normal compacting procedures, by backrolling of slopes with sheepsfoot rollers at frequent increments of 2 to 3 feet in fill elevation gain, or by other methods producing satisfactory results. At the completion of grading, the relative compaction of the slope out to the slope face shall be at least 90 percent. 5.5 Compaction Testing: Field tests to check the fill moisture and degree of compaction will be performed by the consultant. The location and fre- quency of tests shall be at the consultant's discretion. In general, the tests will be taken at an .interval not exceeding 2 feet in vertical rise and/or 1,000 cubic yards of embankment. In addition, on slope faces, at least one test shall be taken for each 5,000 square feet of slope face and/or each 10 feet of vertical height of slope. 6.0 Subdrain Installation Subdrain systems, if required, shall be installed in approved ground to conform to the approximate alignment and details shown on the plans or herein. The subdrai n location or materials shall not be changed or modified without the approval of the consultant. The consultant, however, may recommend and upon approval, direct changes in subdrain line, grade or material. All subdrains should be surveyed for line and grade after installation and sufficient time shall be allowed for the surveys', prior to commencement of filling over the subdrains. 7.0 Excavation Excavations and cut slopes will be examined during grading. If directed by the consultant, further excavation or overexcavation and refilling of cut areas shall be performed, and/or remedial grading of cut' slopes shall be performed. Where fill -over -cut slopes are to be graded, unless otherwise approved, the cut portion of the slope shall be made and approved by the consultant prior to placement of materials for construction of the fill portion of the slope. - 5880127-01 APPENDIX E REFERENCES County of Riverside and Envicom Corporation, Seismic Safety and Safety General Plan Elements, Technical Report, Volumes I and II, dated September 1976. Leighton and Associates, Inc., 1986, "Geotechnical Investigation, Proposed Bank Building, North-east Corner of Avenida Bermudas and Calle Estado, La Qui nta, California", -report dated August 13, 1986, Project No. 5861289-01.