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HomeMy WebLinkAboutCT 83-19; Calavera Hills Village T Pump Station; Soils Report Revised; 1991-05-15-- - - - - - - - - - SOIL INVESTIGATION PROPOSED PUMP STATION CALAVERA HILLS VILLAGE T COLLEGE BOULEVARD CARLSBAD, CALIFORNIA PREPARED FOR Lyon Communities, Incorporated 4330 La Jolla Village Drive Suite 130 San Diego, California 92122 CITY OF CARL&BAD PREPARED BY E~1~@JEERlN@ G;PuiJ”i”ER Southern California Soil and Testing, Incorporated 6280 Riverdale Street San Diego, California 92120 Post Oftice Box 600627, Zip Code 92160 - - - - - - - - - - - SOUTHERN CALIFORNIA SOIL AND TESTING, INC. May 15, 1991 Lyon Communities, Incorporated 4330 La Jolla Village Drive San Diego, California 92122 SCS&T 9021114 Report No. 2-R SUBJECT: Soil Investigation, Proposed Pump Station, Calavera Hills Village T, College Boulevard, Carlsbad, California. Gentlemen: In accordance with your request, we have prepared this soil investigation for the subject project. PROJECT DESCRIPTION It is our understanding that the subject project will consist of a pump station and an access road. The pump station will consist of the following structures: a) Generator building, on-grade, masonry construction. b) Emergency storage tank facility, 17 foot underground, pour-in-place concrete. 4 Pump station and wet well, seven foot underground, pour-in-place concrete. With the exception of cuts for the underground improvements, grading for the proposed pump station pad and the access road will be minor and consist of cuts and fills less than three feet deep. To assist in the preparation of this report, we wme provided with a set of undated improvement plans prepared by Hunsaker and Associates and Robert Hendershot Associates, Inc. The site vicinity, configuration and approximate locations of our subsurface explorations are shown on Plates Number 1 and 2 of this report. .- - SCS&T 9021114 May 15, 1991 FINDINGS Page 2 SITE DESCRIPTION The subject site is located in the, Calavera Hills area of the City of Carlsbad, approximately 700 feet to the east and 100 feet to the south of the proposed cul-de-sac, southern ending of Saddle Drive within the proposed development Calavera Hill Village “T”. More specifically the area of construction is an approximately 1200 foot strip of land trending subparallel to the Calavera Lake-Agua Hedionda Creek drainage. The strip of land, lies along an 30 foot wide general utility easement located on the eastern face of a north to south trending ridge. This hillside has a moderately steep slope to the east, dissected by a very steep sided canyon on the norhtem end of the area to be developed and ending in the nose of the descending ridge to the south. Presently the site supports a moderate to heavy growth of native shrubs and grasses, with occasional man-made debris. GENERAL GEOLOGY AND SUBSURFACE CONDITIONS The subject site is located in the Coastal Plains Physiographic Province of the City of Carlsbad and is underlain by the Cretaceous-age Lusardi Formation, associated topsoils and subsoils, and at depth the Jurrasic-Cretaceous-age granitic bedrock. Three exploratory trenches were excavated within the site to depths ranging from four-and-one-half to nine-feet below existing grade (see Plates Number 2 through 6). In each ~excavation economic to complete refusal was encountered with a 580D case backhoe within the Lusardi Formation, and typically on the very large boulders which make up this formation. Within the excavations the following earth materials were encountered. Topsoils, which consisted of approximately six inches to one foot of, dark brown, moist to wet, clayey silty sands with roots. Subsoils, were encountered underlying the topsoils and extending from approximately six inches to one foot below existing grade to approximately two-and-one-half below existing grade. The subsoils consisted of, dark brown, moist to wet, soft to medium stiff, sandy clay, with fractures. Underlying these surficial deposits the Cretaceous-age Lusardi Formation was encountered in each of our excavations from approximately two-and-one-half-feet below existing grade to the limit of our excavations. The encountered formational materials consisted of weathered granitic boulder and cobble conglomerate with a sand matrix. The boulders and cobbles vary in size with a maximum of approximately two feet in diameter. In general the excavated material consisted of gray tan, humid to moist, medium to coarse sand derived from the decomposed boulders and cobbles. The matrix material consisted of green gray, moist, clayey sand. The in-place density of the entire formation consisted of dense to very dense conglomerate clasts in a loose to medium dense matrix. Refusal was reached in this material on the closely packed large granitic boulder clasts at depths of five feet in trench one, and nine feet in trench two, and a four-and-one-half feet in trench three. - - - SCS&T 9021114 May 1.5, 1991 Page 3 - - .- - - ..- -. Underlying the Lusardi Formation at depth beneath the site is the Jurrasic-Cretaceous-age granitic bedrock, while not exposed in our excavations. Deep excavations may encounter these materials. EXCAVATION CHARACTERISTICS GENERAL: A seismic refraction survey was performed specifically to facilitate the project planning. The seismic survey measures the velocities of soundwaves as they travel through various materials. The velocity of the soundwaves in materials depends on many factors, such as the density, fracture characteristics, moisture condition, etc. Materials such as rock conduct soundwaves at relatively high velocities; whereas, loose materials, such as topsoils, conduct the soundwaves at much lower velocities. By determining the variation in seismic velocity of the underlying materials. This information can be utilized to determine a reasonable approximation of the depth from the existing grade to the boundaries between xippable, marginally rippable, and nonrippable earth materials. The seismograph’s depth of investigation is closely related to the length of the seismic traverse. For a particular length of traverse, e.g., 100 feet, using a ratio of 3:l between length and depth, we conclude that this length of survey line will detect the boundaries between materials of varying density and velocity to a depth of approximately 33 feet. The length of traverses in this survey range from 100 to 120 feet, which should reach a depth of approximately 33 feet to 40 feet. SEISMIC TRAVERSES: Two seismic traverses were performed at the project site in potential cut areas underlain by the Lusardi Formation and granitic bedrock. The locations of the traverses are shown on Plate Number 2. The time versus distance plots of these seismic traverses are presented on Plate Numbers 10 and 11. The apparent velocities were measured at both ends of the seismic traverses, and the seismic traverse performed on the opposite direction is designated letter R. RIPPABILJTY CHARACTERISTICS: The results of our seismic traverses indicate that marginally rippable Lusardi Formation and/or granitic bedrock will be encountered at depths ranging from 15 to 264 feet below existing grade. Marginally rippable to nomippable rock is present below the rippable material. It should be noted that there will be isolated hardrock zones within the rippable materials which may require blasting or heavy ripping to facilitate trenching operations. The thickness of rippable material is highly variable due to the blocky and fractured nature of the rock, and the variation in weathering of the underlying material. Provided below is a brief summary of the rippability characteristics of the Lusardi Formation and granitic bedrock. In addition, the rippable, marginally rippable to nonrippable transition zones described below could be considered gradational in nature with the other respective zones and each varying locally. - - SCS&T 9021114 May 15, 1991 Page 4 - - ..- - -. - Rippable Condition-O to 4,500 fps: This velocity range indicates rippable materials which may consist of Lusardi Formation possessing hardrock boulders and cobbles. Excavation of materials with velocities between about 2,000 and 3,500 fps will generally produce a rocky, silty sand with sufficient fines for use as compacted fill, with some oversized material. Maximum size of rock fragments is expected to be less than two feet. For velocities between about 3,500 and 4,500 fps, excavations are expected to produce small broken rock fragments without sufficient tines to be used as till without mixing. The rock fragments will consist of blocks, boulders or cobbles that can range from less than an inch up to about two feet in diameter. Materials within the velocity range of from 3,500 to 4,000 fps are rippable, but excavations may be difficult for by backhoes and other light trenching equipment. In addition, areas that contain hardrock cobbles and boulders or hardrock areas within the bedrock may be present that will create utility trenching problems. Marginally Rippable Condition-4,500 to 5,500 fps: This velocity range is rippable with increased effort. However, depending on many factors (including the condition of equipment and the operator’s experience), it may or may not be economical. Excavations that can be made in this range are expected to produce a rock/soil mixture that will probably not have sufficient fines to be used as fill and that could contain oversize blocks of the underlying bedrock or very large boulders of the Lusardi Formation. Soils could be mixed with this material to provide enough fines for use as compacted fill. However, the oversize material (blocks over 24 inches in diameter) will need to be removed and disposed of in nonstructural fills. If this type of material is produced by the ripping operation, blasting may be desirable in lieu of excavation by ripping. Blasting is expected to break down the rock into more soil and rock fragments of smaller size that would be suitable for use as fill. Zones of less fractured or weathered materials may also be found in this velocity range that could require blasting to facilitate removal. Materials within this velocity range are beyond the capability of backhoes and lighter trenching equipment. Difficulty of excavation would also be realized by gradalls and other heavy trenching equipment. Therefore, materials with this range of velocities are not desirable for building pad subgrade due to difficulty in footing and utility trench excavation. Nonrippable Condition-greater than 5,500 fps: This velocity range includes nonrippable material consisting primarily of moderately weathered granitic bedrock at lower velocities and only slightly weathered or unweathered rock at higher velocities. Excavations made in blasted rock from this range of velocities are expected to produce a material consisting of 50 to 60 percent rock fragments over six inches in diameter, but generally less than 12 inches. We anticipate that within the lower velocities of this range, mixing with soil will produce a material suitable for use as fill, while the higher velocity material is expected to produce a large quantity of oversize rock. - - - - _-. SCS&T 9021114 May 15, 1991 Page 5 This upper limit has been based on rippability with a Caterpillar D-9L using a conventional #9 Single Shank Ripper. However, this upper limit of rippability may sometimes be increased by using other heavy excavation equipment. The above mentioned rippability limits are based on modification of charts prepared by Caterpillar Company and the article in “Road and Streets,” September 1967. NOTE: According to the Caterpillar Performance Handbook, dated October 1968, the upper limits of rippability has increased over the aforementioned limits. SEISMIC TRAVERSE LIMITATIONS: The results of the seismic survey for this investigation reflect rippability conditions only for the areas of the traverses. However, the conditions of the various soil-rock units appear to be similar for the remainder of the site, and may be assumed to possess similar characteristics. Our reporting is presently limited in that refraction seismic surveys do not allow for prediction of percentage of expected oversize or hardrock floaters. Subsurface variations in the degree of weathering and fracturing are not accurately determinable. The seismic refraction method requires that materials become increasingly dense with depth. In areas where denser, higher velocity materials are underlain by lower velocity materials, the lower velocity materials would not be indicated by our survey. All of the velocities used as upper limits are subject to fluctuation depending upon such local variations in rock conditions as: 4 The characteristics of fractures, faults, and other planes of weakness; b) The degree of weathering; ; The brittleness and crystalline nature; The mineral grain size. It should be noted that ripping of higher velocity materials may become totally dependent on the time available and the economics of the project. Ripping of higher velocity materials can be achieved but it may become economically infeasible. CONCLUSIONS AND RECOh,lMENDATIONS GENERAL In general, no geotechnical conditions were encountered which would preclude the construction of the proposed pump station provided the recommendations presented herein are followed. The site is underlain by up to 2.5 feet of compressible topsoil and subsoils. These deposits are considered unsuitable, in their present condition, for the support of settlement sensitive improvements and will require removal and replacement as compacted till. The subsoils are highly expansive. Two seismic traverse line were performed at and near the locations of the .- - - SCS&T 9021114 May 15, 1991 Page 6 - proposed underground improvements. The traverse lines indicate that the soil in this area may be excavated with special trenching equipment without blasting. Although most of the on-site boulders and cobbles are highly weathered and crumble into coarse sand, it is anticipated that proposed grading operations will generate boulders requiring special off-site disposal. GRADING SITE PREPARATION: Site preparation should begin with the removal of any existing vegetation and deleterious matter. Existing topsoils and subsoil deposits underlying proposed settlement-sensitive improvements should be removed to firm natural ground. Based on our findings, it is anticipated that maximum removal depth will be 2.5 feet. The soils exposed at the bottom of the excavation should be scarified to a depth of 12 inches, moisture conditioned and recompacted to at least 90 percent as determined in accordance with ASTM D-1557-78, Method A or C. Limits of removal should be five feet beyond the perimeter of the improvements. SURFACE DRAINAGE: It is recommended that all surface drainage be directed away from the structures and the top of slopes. Ponding of water should not be allowed adjacent to the foundations. EARTHWORK: All earthwork and grading contemplated for site preparation should be accomplished in accordance with the attached Recommended Grading Specifications and Special Provisions. All special site preparation recommendations presented in the sections above will supersede those in the Standard Recommended Grading Specifications. All embankments, structural fill and fill should be compacted to at least 90% relative compaction at or slightly over optimum moisture content. Utility trench backfill within five feet of the proposed structures and beneath asphalt pavements should be compacted to a minimum of 90 percent of its maximum dry density. The upper twelve inches of subgrade beneath paved areas should be compacted to 95 percent of its maximum dry density. This compaction should be obtained by the paving contractor just prior to placing the aggregate base material and should not be part of the mass grading requirements. The maximum dry density of each soil type should be determined in accordance with ASTM Test Method D - 1557-78, Method A or C. TEMPORARY CUT SLOPES - .- Temporary cut slopes up to 17 feet in height are anticipated. The following table provides temporary cut slope recommendations. - - SCS&T9021114 May 15, 1991 Page 7 - - - - .- - TEMPORARY CUT SLOPES SLOPE HEIGHT (feet) 5 10 20 * Continuous Inclination SLOPE INCLINATION* (horizontal to vertical) vertical 0.5:1 0.75: 1 Due to the cobble and boulder content of the existing soils it is recommended that temporary cut slopes be covered with wire mesh. All temporary cut slopes should be approved by a representative from this office. No surcharge loads should be allowed within a distance from the toe of the slope equal to its height. FOUNDATIONS GENERAL: Shallow foundations may be utilized for the support of the proposed structures. The footings should have a minimum depth of 12 inches below lowest adjacent finish pad grade. A minimum width of 12 inches and 24 inches is recommended for continuous and isolated footings, respectively. A bearing capacity of 2000 psf may be assumed for on-grade footings. For underground improvements a bearing capacity of 3500 may be assumed. These bearing capacities may be increased by one-third when considering wind and/or seismic forces. REINFORCEMENT: Both exterior and interior continuous footings should be reinforced with two No. 5 bars (or one No. 6) positioned near the bottom of the footing and two No. 5 bars (or one No. 6) positioned near the top of the footing. This reinforcement is based on soil characteristics and is not intended to be in lieu of reinforcement necessary to satisfy structural considerations. CONCRETE SLABS-ON-GRADE: Concrete slabs-on-grade should have a thickness of five inches and be underlain by a four-inch blanket of clean, poorly graded, coarse sand or crushed rock. This blanket should consist of 100 percent material passing the half-inch screen and not more than 25 percent, ten percent and five percent passing sieves #16, #lOO and #200, respectively. The slab should be reinforced with No. 3 reinforcing bars placed at 12 inches on center each way extending 12 inches into the footings. Slab reinforcement should be placed within the middle third of the slab. Where moisture-sensitive floor coverings are planned, a visqueen barrier should be placed on top of the sand layer. A two-inch-thick layer of clean sand should be placed over the visqueen to allow proper concrete curing. SPECIAL CONSIDERATIONS: Special requirements determined by the manufacturers in excess of the aforementioned recommendations should be implemented. - - - SCS&T 9021114 March 19, 1991 Page 8 EXPANSIVE CHARACTERISTICS: The prevailing foundation soils were found to range from nondetrimentally to highly expansive. The recommendations contained in this report are applicable to a highly expansive condition. - SETTLEMENT CHARACTERISTICS: The anticipated total and/or differential settlements for the proposed structures may be considered to be within tolerable limits provided the recommendations presented in this report are followed. It should be recognized that minor cracks normally occur in concrete slabs and foundations due to shrinkage during curing or redistribution of stresses and some cracks may be anticipated. Such cracks are not necessarily an indication of excessive vertical movements. EARTH RETAINING STRUCTURES PASSIVE PRESSURE: The passive pressure for the prevailing soil conditions may be considered to be 450 pounds per square foot of depth up to a maximum of 400 psf. This pressure may be increased one-third for seismic loading. The coefficient of friction for concrete to soil may be assumed to be 0.3 for the resistance to lateral movement. When combining frictional and passive resistance, the latter should be reduced by one-third. ACTIVE PRESSURE: The active soil pressure for the design of earth retaining structures with level backfills may be obtained from the following diagrams. These values assume a granular and drained backfill condition. Waterproofing and subdrain recommendations should be provided by the project architect. - - - - - H PSF O.lH -L t 0.2H ACTIVE PRESSURE DIAGRAMS No Scale - -, - SCS&T 9021114 May 15, 1991 Page 9 .~ - ,- - - - - - BACKFILL: All backfill soils should be compacted to at least 90 percent relative compaction. Expansive or clayey soils should not be used for backfill material. The retaining structure should not be backfilled until the materials in the wall have reached an adequate strength. LIMITATIONS The recommendations and opinions expressed in this report reflect our best estimate of the project requirements based on an evaluation of the subsurface soil conditions encountered at the subsurface exploration locations and the assumption that the soil conditions do not deviate appreciably from those encountered. It should be recognized that the performance of the foundations and/or cut and fill slopes may be influenced by undisclosed or unforeseen variations in the soil conditions that may occur in the intermediate and unexplored areas. Any unusual conditions not covered in this report that may be encountered during site development should be brought to the attention of the soils engineer so that he may make modifications if necessary. In addition, this office should be advised of any changes in the project scope or proposed site grading so that it may be determined if the recommendations contained herein are appropriate. This should be verified in writing or modified by a written addendum. If you have any questions after reviewing this report, please do not hesitate to contact this office. This opportunity to be of professional service is sincerely appreciated. AND TBSTING, INC. DBA:mw cc: (2) Submitted (3) Hunsaker and Associates (1) Robert Hendershot Associates, Inc. (1) SCS&T, Escondido - - - SOUTHERN CALIFORNIA VILLAGE T PUMP STATION SOIL & TESTING, INC. F*: WA/EM DATE: 3-19-91 . . ..s.-mm. 9021114 PLATE X 1 SUBSURFACE EXPLORATION LEGEND SOIL DESCRIPTION GROUP SYMBOL TYPICAL NAMES . COARSE GRAINEO. rare than half I of material is.- than NO. 200 sieve s17.e. RAVELS ii CLEAN GRAVELS GW Uell graded gravels, gravel- ore t"a" half of sand mixtures. little or no c oarsc fraction is fines. 1 arger than No. 4 GP Poorly graded gravels, gravel s ieve size but sand mixtures, little or no s Ml1.w than 3". i<nar I Il.Ca. GRAVELS WITH FINES GM Silty gravels. poorly graded (Appreciable amount gravel-sand-silt mixtures. of fines) GC Clayey gravels. poorly waded aravel-sand. clay r&xture;. : ANQS CLEAN SANDS SA orethan half of Uell graded sand, gravelly sands. little or no fines. c oarse fraction is SP Poorly graded sands. gravelly * mailer than No. 4 sands, litile or no fines. 5 ievc size. SANOS YITH FINES St4 Silty sands. poorly graded IAppreciable amount sand and silty miXtUres. of fines.1 SC Clayey sands. poorly graded sand and clay mixtures. I I. FINE GRAINEO. more than half of material is smaller than No. 200 sieve s12e. SILTS AND CLAYS NL Inorganic silts and very fine sands. rock flour. sandy silt or cl:?'ey-silt-sand mixtures with slioht alas- - ticity. Liquid Limit CL Imrganic c:dys of low to less than 50 medium plasticity. graW?lly clays, sandy clays,.silty clays, lean clays. OL Organic silts and organic silty clays or low plasticity SILTS AN0 CLAYS NH Inorganic silts, micaceous or diatomaceour fine sandy or silty soils. elastic silts. Liquid Limit CH Inorganic clays of high greater than 50 plasticity. fat clays. OH Organic clays of mdium to high plasticity. HIGHLY ORGANIC SOILS PT Peat and other highly L organic soils. - z- Water level at time of excavation CK - Undisturbed chunk sample or as indicated i3G - Bulk sample US - Undisturbed. driven ring sample SP - Standard penetration sample or tube sample SOUTHERN CALIFORNIA VILLAGE T PUMP STATION SOIL & TESTIWO, INC. I)*: DBA DATEz 3-19-91 JOB NUl#lEl3:9021114 Plate No. 3 UNIFIED SOIL CLASSIFICATION CHART - - - - - .- - .- - - - T i! i5 E E 5 TRENCH NUMBER 1 5; SYb p> z !ii $# ELEVATION w3 wwz 25 E % 3 Sk Zt SLZ wu P- aa0 OS s p: 4: 4g= g d DESCRIPTION o” 0 0 SW TOPSOIL, Dark Brown, CLAYEY Moist to Loose SC SILTY SAND Wet 1 BG cL SUBSOIL, Dark Brown, SANDY Wet Soft CLAY 2 CK Moist Medium 3-l Stiff GM/ LUSARDI FORMATION, Grey Tan, Humid Dense to BG Gp Slightly SILTY SANDY GRAVEL Very 4- with Cobble and Boulders, Dense _ CK Maximum Size 2', Cobbles and Boulders Highly Weathered, 5- Most Crumble into SAND Trench Ended at 5' SOUTHERN CALIFORNIA PROJECT: VILLAGE T PUMP STATION SOIL 8 TESTING. INC. LOOOLD Ev: JWR DATE LOOOED: 3-07-91 JOB YUYmEII: 9021114 PLATE NUYEER: 4 l-' w BG 2- 3- 4- CK 5- 6- CK 7- a- CF 9-1 SM/ SP rRENCH NUMBER 2 iLEVATlON DESCRIPTION TOPSOIL, Dark Brown, CLAYEY SILTY SAND Moist Wet SUBSOIL, Medium Brown, SANDY Moist to CLAY Wet LUSARDI FORMATION, Tan, SILTY SANDY GRAVEL with Cobble and Boulders, Maximum Size 1.5'. Cobbles and Boulders Highly Weathered, Most Crumble into SAND Trench Ended at 9' Humid Loose Soft to Medium Stiff Medium Dense -- Dense -- Very Dense I SOUTHERN CALIFORNIA PROJECT: VILLAGE T PUMP STATION SOIL 8 TESTING. INC. LOOOED BY: JWR DATE LOOOED: 3-07-91 JOB NUYDER: 9021114 PLATE NUYIE”: 5 - ? ttf 5 t c w i i 2 5 w I-- l-' Z- 3- 4- 5- iP/ iM ‘RENCH NUMBER 3 LEVATION DESCRIPTION TOPSOIL, Dark Brown, CLAYEY jILTY SAND jUBSOIL, Brown, SANDY CLAY .USARDI FORMATION, Tan, Slightly CLAYEY SANDY GRAVEL #ith Cobble and Boulders, 4aximum Size 2', Most Cobble lnd Boulders Highly deathered, Most Crumble into SAND Economic Refusal at 4.5' CW ZK W3 2: P- :B loist to let foist to let loist *> GC wwz 555 -0 %$ *0= 00 .oose joft t0 ledium stiff ledium lense SOUTHERN CALIFORNIA PaOJECT: VILLAGE T PUMP STATION SOIL 8 TESTING, INC. LOQOED BY: JWR DATE LOOOCD: 3-07-91 JO0 NUYBER: 9021114 PLATE NUYaCII: 6 I I / I I / I I I I I I I b U.S. STAWARD SYVES HYDROMETER omuTw 36’ IV 2’ I. 112. I,.. ,,o ,20 1.0 160 a*0 1 q -s - , 2 * *a 2 GRAIN SIZE (mm) PARTICLE SIZE LIMITS I EKNkDER~ COBBLE GRAVEL I SAW0 SLT OR CLAY I COARSE FWY COARSE W3JlUN FWE (12’) 3 314 No. 4 No. 10 No. 40 _. _-- “0. zoo U.S. STANDARD SIEVE SIZE T2 @ 3’-9 MAXIMUM DENSITY 8, OPTIMUM MOISTURE CONTENT - ,- -. .~- - __ EXPANSION INDEX TEST RESULT .- - -, - .- -- DIRECT SHEAR SUMMARY 2Y L NORM: STRESS, KSF ANWE OF INTERNAL COHESION INTERCEPT SAMPLE DESCWPTION FRlCTlON (‘1 (Pro T2 @ 3'-9' Remolded to 90% 43 100 SOUTHERN CALIFORNIA VILLAGE T PUMP STATION SOIL & TISTINQ,INC. IIV': DBA OAT,?: 3-19-91 JO,NUY~EO: 9021114 Plate No. 9 n L 10 20 30 40 50 60 70 80 loo - 20 40 60 20 100 I30 140 160 200 _-- _.- __- * 30 60 SO:T!i 120 150 100 110 140 270 300 DISTANCE ----+ NORTH - 108 Village T .~ __ GEOLOGIST JWR _- _ SOUTHERN CALIFORNIA JOB NO. 9021114 ELEVATION .~-- SOIL &TESTING, INC. TRAVERSE NO. --?I!~ ~~~~~~__ SURFICIAL MAT’L. Lusardi Formation ~--__~---- TRAVERSE TYPE __- Seismic ROCK TYPE Kqr-mmpe-~~~---.. I I I IW 120 60 120 loo So 130 30 40 906030 69 40 30 10 39 30 40 50 60 70 80 99 100 40 60 80 100 120 140 160 180 200 60 90 120 150 180 210 240 270 300 DISTANCE - NW- SE SOUTHERN CALIFORNIA JOB NO. 9021114 ELEVATION .-__ SOIL &TESTING, INC. TRAVERSE NO. ~~~~~ s-2 SURFICIAL MAT’L. ~-..-~ Lusardi Format_jgF_ ~~~~~~._-- IOB Village T ~~~__ CEOLOClST~~-mm JWR TRAVERSE TYPE ~ __..._. ~~__ ROCK TYPE -.-w .- -. PUMP STATION, CALAVERA HILLS VILLAGE T, CARLSBAD RECOMMENDED GRADING SPECIFICATIONS - GENJZRAL PROVISIONS GENERALINTENT ,- The intent of these specifications is to establish procedures for clearing, compacting natural ground, preparing areas to be tilled, and placing and compacting till soils to the lines and grades shown on the accepted plans. The recommendations contained in the preliminary geotechnical investigation report and/or the attached Special Provisions are a part of the Recommended Grading Specifications and shall supersede the provisions contained hereinafter in the case of conflict. These specifications shall only be used in conjunction with the geotechnical report for which they are a part. NO deviation from these specifications will be allowed, except where specified in the geotechnical report or in other written communication signed by the Geotechnical Engineer. - OBSERVATION AND TESTING - Southern California Soil and Testing, Inc., shall be retained as the Geotechnical Engineer to observe and test the earthwork in accordance with these specifications. It will be necessary that the Geotechnical Engineer or his representative provide adequate observation so that he may provide his opinion as to whether or not the work was accomplished as specified. It shall be the responsibility of the contractor to assist the Geotechnical Engineer and to keep him appraised of work schedules, changes and new information and data so that he may provide these opinions. In the event that any unusual conditions not covered by the special provisions or preliminary geotechnical report are encountered during the grading - operations, the Geotechnical Engineer shall be contacted for further recommendations. If, in the opinion of the Geotechnical Engineer, substandard conditions are encountered, such as questionable or unsuitable soil, unacceptable moisture content, inadequate compaction, adverse weather, etc.; construction should be stopped until the conditions are remedied or corrected or he shall recommend rejection of this work. Tests used to determine the degree of compaction should be performed in accordance with the following American Society for Testing and Materials test methods: Maximum Density & Gptimum Moisture Content - ASTM D-1557-78. Density of Soil In-Place - ASTM D-1556-64 or ASTM D-2922. All densities shall be expressed in terms of Relative Compaction as determined by the foregoing ASTM testing procedures. - - (R-9189) -- SCS&T 9021114 March 19, 1991 Appendix, Page 2 PREPARATION OF AREAS TO RECEIVE FILL All vegetation, brush and debris derived from clearing operations shall be removed, and legally disposed of. All areas disturbed by site grading should be left in a neat and fmished appearance, free from unsightly debris. After clearing or benching the natural ground, the areas to be filled shall be scarified to a depth of 6 inches, brought to the proper moisture content, compacted and tested for the specified minimum degree of compaction. All loose soils in excess of 6 inches thick should be removed to firm natural ground which is defined as natural soils which possesses an in-situ density of at least 90 percent of its maximum dry density. When the slope of the natural ground receiving fill exceeds 20 percent (5 horizontal units to 1 vertical unit), the original ground shall be stepped or benched. Benches shall be cut to a firm competent formational soils. The lower bench shall be at least 10 feet wide or l-112 times the equipment width, whichever is greater, and shall be sloped back into the hillside at a gradient of not less than two (2) percent. All other benches should be at least 6 feet wide. The horizontal portion of each bench shall be compacted prior to receiving fill as - specified herein for compacted natural ground. Ground slopes flatter than 20 percent shall be benched when considered necessary by the Geotechnical Engineer. - ..~ Any abandoned buried structures encountered during grading operations must be totally removed. All underground utilities to be abandoned beneath any proposed structure should be removed from within 10 feet of the structure and properly capped off. The resulting depressions from the above described procedures should be backfilled with acceptable soil that is compacted to the requirements of the Geotechnical Engineer. This includes, but is not limited to, septic tanks, fuel tanks, sewer lines or leach lines, storm drams and water lines. Any buried structures or utilities not to be abandoned should be brought to the attention of the Geotechnical Engineer so that he may determine if any special recommendation will be necessary. All water wells which will be abandoned should be backfilled and capped in accordance to the requirements set forth by the Geotechnical Engineer. The top of the cap should be at least 4 feet below finish grade or 3 feet below the bottom of footing whichever is greater. The type of cap will depend on the diameter of the well and should be determined by the Geotechnical Engineer and/or a qualified Structural Engineer. FILLMATERIAL Materials to be placed in the fill shall be approved by the Geotechnical Engineer and shall be free of vegetable matter and other deleterious substances. Granular soil shall contain sufficient fine material to fill the voids. The definition and disposition of oversized rocks and expansive or detrimental soils are covered in the geotechnical report or Special Provisions. Expansive soils, soils of poor gradation, or soils with low strength characteristics may be thoroughly mixed with other soils to provide satisfactory fill - (R-9189) SCS&T 9021114 March 19, 1991 Appendix, Page 3 material, but only with the explicit consent of the Geotechnical Engineer. Any import material shall be approved by the Geotechnical Engineer before being brought to the site. PLACING AND COMPACTION OF FILL -. .- - - ..-. - ,- - - Approved till material shall be placed in areas prepared to receive fill in layers not to exceed 6 inches in compacted thickness. Each layer shall have a uniform moisture content in the range that will allow the compaction effort to be efficiently applied to achieve the specified degree of compaction. Each layer shall be uniformly compacted to the specified minimum degree of compaction with equipment of adequate size to economically compact the layer. Compaction equipment should either be specifically designed for soil compaction or of proven reliability. The minimum degree of compaction to be achieved is specified in either the Special Provisions or the recommendations contained in the preliminary geotechnical investigation report. When the structural till material includes rocks, no rocks will be allowed to nest and all voids must be carefully tilled with soil such that the minimum degree of compaction recommended in the Special Provisions is achieved. The maximum size and spacing of rock permitted in structural tills and in non-structural fills is discussed in the geotechnicai report, when applicable. Field observation and compaction tests to estimate the degree of compaction of the fill will be taken by the Geotechnical Engineer or his representative. The location and frequency of the tests shall be at the Geotechnical Engineer’s discretion. When the compaction test indicates that a particular layer is at less than the required degree of compaction, the layer shall be reworked to the satisfaction of the Geotechnical Engineer and until the desired relative compaction has been obtained. Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment. Compaction by sheepsfoot rollers shall be at vertical intervals of not greater than four feet. In addition, till slopes at a ratio of two horizontal to one vertical or flatter, should be trackrolled. Steeper fill slopes shall be over-built and cut-back to fmish contours after the slope has been constructed. Slope compaction operations shall result in all fill material six or more inches inward from the finished face of the slope having a relative compaction of at least 90 percent of maximum dry density or the degree of compaction specified in the Special Provisions section of this specification. The compaction operation on the slopes shall be continued until the Geotechnical Engineer is of the opinion that the slopes will be stable surficially stable. Density tests in the slopes will be made by the Geotechnical Engineer during construction of the slopes to determine if the required compaction is being achieved. where failing tests occur or other field problems arise, the Contractor will be notified that day of such conditions by written communication from the Geotechnical Engineer or his representative in the form of a daily field report. (R-9189) - SCS&T 9021114 March 19, 1991 Appendix, Page 4 - - ~- - .- - - - - - - - If the method of achieving the required slope compaction selected by the Contractor fails to produce the necessary results, the Contractor shall rework or rebuild such slopes until the required degree of compaction is obtained, at no cost to the Owner or Geotechnical Engineer. CUT SLOPES The Engineering Geologist shall inspect cut slopes excavated in rock or lithified formational material during the grading operations at intervals determined at his discretion. If any conditions not anticipated in the preliminary report such as perched water, seepage, lenticular or confined strata of a potentially adverse nature, unfavorably inclined bedding, joints or fault planes are encountered during grading, these conditions shall be analyzed by the Engineering Geologist and Soil Engineer to determine if mitigating measures are necessary. Unless otherwise specified in the geotechnical report, no cut slopes shah be excavated higher or steeper than mat allowed by the ordinances of the controlling governmental agency. ENGINEERING OBSERVATION Field observation by the Geotechnical Engineer or his representative shall be made during the filling and compacting operations so that he can express his opinion regarding the conformance of the grading with acceptable standards of practice. Neither the presence of the Geotechnical Engineer or his representative or the observation and testing shall not release the Grading Contractor from his duty to compact all fill material to the specified degree of compaction. SEASON LIMITS Fiil shall not be placed during unfavorable weather conditions. When work is interrupted by heavy rain, filling operations shall not be resumed until the proper moisture content and density of the fill materials can be achieved. Damaged site conditions resulting from weather or acts of God shall be repaired before acceptance of work. RECOMhlENDED GRADING SPECIFICATIONS - SPECIAL PROVISIONS RELATIVE COMPACTION: The minimum degree of compaction to be obtained in compacted natural ground, compacted till, and compacted backfill shah be at least 90 percent. For street and parking lot subgrade, the upper six inches should be compacted to at least 95 percent relative compaction. (R-9189) SCS&T 9021114 March 19, 1991 Appendix, Page 5 - EXPANSIVE SOILS: Detrimentally expansive soil is defined as clayey soil which has an expansion index of 50 or greater when tested in accordance with the Uniform Building Code Standard 29-C. OVERSIZED MATERIAL: Oversized fill material is generally defined herein as rocks or lumps of soil over 6 inches in diameter. Oversize materials should not be placed in fill unless recommendations of placement of such material is provided by the geotechnical engineer. At least 40 percent of the till soils shall pass through a No. 4 U.S. Standard Sieve. - - - - - - - - - TRANSITION LOTS: Where transitions between cut and fill occur within the proposed building pad, the cut portion should be undercut a minimum of one foot below the base of the proposed footings and recompacted as structural backfdl. In certain cases that would be addressed in the geotechnical report, special footing reinforcement or a combination of special footing reinforcement and undercutting may be required. - (R-9/89)