HomeMy WebLinkAboutCT 75-04; La Costa Estates North Lot 34; Soils Report; 1985-07-17GEOTECHNICAL INVESTIGATION FOR .5 ACRE LOT ON BOLERO STREET
LOT 34 OF CARLSBAD TRACT 15-4, LA COSTA. ESTATES NORTH, NAP 8302
PREPARED FOR:
MR. ED EGINTON 515 S. GRANADOS SOLANA BEACH, CALIFORNIA 92075
ENGINEERING DEPT. LIBRARY Ciiy of Carlsbad 2075 Las Palmas Drive
CarlsbaQ CA92009-4859
PREPARED BY:
SAN DIEGUITO SOILS, INC. 4407 MANCHESTER AVENUE, SUITE 101 ENCINITAS, CALIFORNIA 92024
Revised Letter and First Page 2/17/86 July 17, 1985
Mr. Ed Eginton 515 S. Granados Solana Beach, California 92075 SDS 7578
GEOTECHNICAL INVESTIGATION FOR .5 ACRE LOT ON BOLERO STREET IN LA COSTA, CALIFORNIA, LOT 34 OF CARLSBAD TRACT 75-4, IA COSTA ESTATES NORTH, MAP 8302 Gentlemen:
We are pleased to present the results of our geotechnical inves- ticja.tion for the subject project. This study was performed ii] accordance wit:? your request.
The accompanying report presents our conclusions and recommenda- tions pertaining to the site, as well as the results of our field explorations and laboratory tests.
In general, we found the site to be suitable for the proposed development provided the recommendations contained in the body of this report are followed. However, loose expansive soils on this site will require special design considerations.
If you have any questions after reviewing this report, please do not hesitate to contact this office. This opportunity to be of service is greatly appreciated.
Respectfully Submitted, SAN DIEGUITO SOILS, INC.
.C.E. 26525
ation Expires 3/31/86
JBF/cj
Tim Slotta Project Geologist
INTRODUCTION AND PROJECT DESCRIPTION
PROJECT SCOPE
BACKGROUND INFORMATION
FIELD INVESTIGATION
LABORATORY TESTING
Surface Conditions Geologic Setting Subsurface Conditions
POTENTIAL GEOLOGIC HAZARDS
Surficial Slope Stability Groundwater
CONCLUSIONS
RECOMMENDATIONS
Site Preparation Foundations and Floor Slabs Cut and Fill Slopes Retaining Walls and Lateral Loads Pavement
LIMITATIONS
Plate 1 Vicinity Map Plate 2 Site Plan Plate 3 Unified Soil Classification Plates 4 - 7 Logs of Trenches Plate 8 Laboratory Test Results Plate 9 Weakened Plane Joint Diagram
Appendix A Recommended Grading Specifications
Paae Number
1
1
‘2
2
3
4
4
4
4
5
::
7
8
i 10 11 12
12
.,,.
,,
GEOTECBNICAL INVESTIGATION FOR .5 ACRE LOT ON BOLERO STREET LOT 34 OF CARLSBADTRACT 75-4, LA COSTA ESTATES NORTH, MAP 8302
UCTI-ROJECT DESC-
This report presents the results of our geotechnical investiga- tion at the site of the proposed development. The site is lo- cated on a gentle southward sloping hillside bordering Bolero Street in La Costa, California. The project is bordered to the north, south and east by recently developed residential lots.
It is our understanding that the site is to be developed by-grad- i il g the site and by the construction of a single ramily residence.
To assist in the preparation of this report, we were provided with a tax plat prepared by the County of San Diego. The site configuration and locations of our subsurface explorations are shown on the site plan on Plate Number 2 of this report.
PROJECT SCOPE
This investigation consisted of surface reconnaissance, subsur- face explorations, obtaining representative disturbed and undis- turbed samples, laboratory testing, analysis of the field and laboratory data, research of available geological literature per- taining to the site, and preparation of this report. Specifically, the intent of this study is to:
a)
b)
c)
d)
Explore the subsurface conditions to the depths in- fluenced by the proposed construction.
Evaluate, by laboratory tests, the pertinent engineer- ing properties of the various strata which will in- fluence the development, including their bearing capacities, expansive characteristics and settlement potential.
Define the general geology at the site including pos- sible geologic hazards which could have an effect, on the site development.
Develop soil engineering criteria for site grading and provide design information regarding the stability of cut and fill slopes.
SDS 7578 July 17, 1985 Page 2
e) Determine potential construction difficulties and provide recommendations concerning these problems.
f) Recommend an appropriate foundation system for the type of structures anticipated and develop soil engineering design criteria for the recommended foundation design.
UND INFORMA-
To aid in our investigation we have reviewed the following maps and reports:
County of San Diego Orthophoto 200 scale Topography, Sheet No. 314-1713, photograptied in 1973.
"Faults and Epicenters", prepared by the County of San Diego, 1973.
"Maximum Credible Rock Acceleration from Earthquakes in California", California Division of Mines and Geology, Map Sheet 23. R.W. Greensfelder 1974.
Report No. 123! "Character and Recency of Faulting San Diego Metropolitan Area, California", published by the California Division of Mines and Geology.
Our field investigation was performed on July 2, 1985, and con- sisted of a visual reconnaissance of existing surface conditions and the excavation of four test trenches on the property ranging in depth from 3 to 5 feet. The approximate ~locations of the ex- cavations are shown on the attached Site Plan, Plate No. 2. The test trenches were excavated with a backhoe using an 24-inch wide bucket. The excavations were made under the supervision of a project geologist from this office. Field logs were prepared on the basis of the samples secured and the excavated material. The logs of the trenches are presented on Plates No. 4 through 7. Soils were classified visually according to the Unified Soil Classification System. Representative soil samples were obtained from the test trenches and were transported to the laboratory for inspection and testing.
SDS 7578 July 17, 1985 Page 3
Laboratory tests were performed in accordance with the generally accepted American Society for Testing and Materials (A.S.T.M.) test methods or suggested procedures. A brief description of the tests performed is presented below:
=I Moisture-Densitvi Field moisture content and dry den- sity were determined for representative samples obtained. This information was an aid in class- ification and permitted recognition of variations in
material consistency with depth. The dry unit weight is deter3ln-d in pounds per cubic fodt, and the r‘iel> moisture content is determined as a Ferceccage of the soil's dry weight. The results are summarized in the trench logs.
b) Classification: Field classifications were verified in the laboratory by visual examination. The final soii classifications are in accordance wii-iI the Unified Soil Ciassification System.
c) Direct Shear Test: Direct shear tests were performed to determine the failure envelope based on yield shear strength. The shear box was designed to accommodate a sample having diameters of 2.375 inches or 2.50 inches and a height of 1.0 inch. Samples were tested at dif- ferent vertical loads and at saturated moisture content. The shear stress was applied at a constant rate of strain of approximately 0.05 inches per minute. The results of these tests are presented in the at- tached Plate No. 8.
d) Compaction Test: The maximum dry density and optimum moisture content of typical soils were determined in the laboratory in accordance with A.S.T.M. Standard Test D-1557-70, Method A. The results of these tests are presented on the attached Plate No. 8.
-=I Exp nsion Ts!.atz The expansive potential of the prin- tip% soil was determined in accordance with the fol- lowing test procedure and the results of these tests appear on Plate No. 8. Allow the trimmed, undisturbed or remolded sample to air dry to a constant moisture content, at a temperature of 100 degrees F. Place the dried sample in the consolidometer and allow to compress under a load of 150 psf. Allow moisture to ,~ contact the sample and measure its expansion from air dried to saturated condition.
SDS 7578 July 17, 1985 Page 4
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. Surface Condition8
The site exists on a gentle southward sloping hillside in La Costa, California. It has been a dumpsite of excess soil from surrounding grading projects. The fili is restricted to the western half of the lot and exists as approximately three foot high piles caused by dump trucks. The raainder of the site is covered by small scrub brush and grasses,
Geoloaic Setting
The San Diego area is characterixed by Tertiary and early Quater- nary sedimentary deposits capped by late Quaternary marihe ant: non-marine terrace deposits. The Tertiary and Quaternary sedimentary formations were deposited on a basement of complexly deformed Jurassic age metavolcanic rocks intruded by Cretaceous batholithic rocks. In most places, the basement rocks have acted as a rigid platform from the Cretaceous period to the present. The Tertiary and Quaternary sedimentary formations deposited upon the basement rocks are nearly flat-lying except for highly deformed areas, such as Mount Soledad. Late Quaternary erosion produced the incised major and minor drainage systems in the area. This erosion surface has also been modified by~late Quaternary faulting.
Eill; The fill is composed of material generated from grading projects of surrounding areas. It is a brown, silty to clayey medium sand with metavolcanic cobbles. The fill is loose and dry and should be removed or recompacted per the attached recommendations.
Mstavolcanics . The metamorphosed metavolcanic rocks are the oldest of the rock units at the site. They consist of a dense, yet fractured, dark gray, fine grained hornfels. The extent of the rocks is limited. They are noted in the road cut along El Fuerte and appear in isolated outcrops along Alga Road.
t
SDS 7578 July 13, 1985 Page 5
The topsoil generally consists of a brown, silty sand or a brown, sandy clay with metavolcanic cobbles. The thickness of the topsoil ranges across the site, but is generally one and a half to two feet in depth. The topsoils are loose, dry, and when clay, highly expansive.
GEOV
The potential geologic hazards of the site were evaluated on the basis of a brief geologic reconnaissance of the site and review- ing the geologic literature including Suiletin 200, "Geology of the San Diego Metropolitan Area, Califcrnia", punlishecl by the Ca;iforfiia Di,;isii)r, of Mines ar,b Geo!.o.,ty ar.d "F.:z;ts ar:d EpiCent-zs", prepared by the County of San giego. The findings are discussed in the following sections of this report.
The California 3ivision of Mines and Geology (Zart, 1975) has es- tablished the following definitions fcr fault activity:
&&ive - I. . . faults which have had surface displacement within Holocene time (last 11,000 years) . . ."
Eodntiallv Active - ". . . any fault considered to have been active during Quaternary time (last 2 to 3 million years . .I displacemeit. . on the basis of evidence of surface .An exception is a Quaternary fault which is determined, from direct evidence, to have become inactive before Holocene time (approximately last 11,000 years). Such faults are assumed to be essentially inactive. . ."
"The State Geologist has identified potentially active faults in a broad sense, and the evidence for potential ac- tivity of some faults may be only weak or indirect."
Uactive - I. . . a Quaternary fault which is determined, from direct evidence, to have become inactive before Holocene time (approximately 11,000 years). . . (is) assumed to be essentially inactive. . ."
We have used these definitions as a basis for fault activity in this report.
It should be recognised that much of the Southern California and NorthernBaja California region is characterized by major, active fault zones that could possibly affect the subject site. The major fault systems in the region include the San Andreas, San Jacinto and Elsinore Fault Zones to the east and north; the San
.
SDS 7578 July 17, 1985 Page 6
Clemente Fault Zone to the west, and Agua Blanca and San Miguel Fault Zone to the south.
The site is located in an area which is relatively free of poten- tial geologic hazards. Hazards such as tsunamis, seiches or liquefaction should be considered negligible or nonexistent.
The most likely geologic hazard to affect the site is groundshak- ing as a result of movement along one of the major, active fault zones mentioned above. The maximum bedrock accelerations that would be attributed to a maximum orobable earthquake occurrins along the nearest portion of the iault zones that the site are summarized in the following table: could affect
TABLE I
Max. Probable Fault Zone classification Distance Earthquake
Rose Canyon
La Nation
Elsinore
San Jacinto
Agua Blanca- San Clemente
Vallecitos San Miguel
Potentially 6 Miles 6.0 Magnitude Active
Potentially 18 Miles 6.0 Magnitude Active
Active 27 Miles 7.3 Magnitude
Active 52 Miles 7.8 Magnitude
Active 49 Miles 7.5 Magnitude
Active 50 Miles 7.5 Magnitude
Max. Bedrock Earthauak_f:
0.35 g.
0.08 g.
0.19 g.
0.11 g.
0.10 g.
0.10 g.
Based on the current fault zone classification, and the maximum bedrock accelerations capable of developing, it is recommended that the Elsinore Fault Zone be considered the design earthquake source for the subject development. Although a maximum probable earthquake along the Rose Canyon Fault zone could conceivably produce ground motions considerably stronger than those that would be attributed to the Elsinore Fault Zone, it is our opinion that, due to the current classification of this local fault zone as potentially active rather than active, it should not be used as the design earthquake source for standard residential structures.
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SDS 7570 July 17, 1985 Page 7
It should be noted that water is known to reduce the strength of earth materials. Adverse drainage and the intrusion of water into hillside areas, control over both surface runoff and adverse groundwater conditions should be maintained. In addition, graded slopes should be planted soon after construction and maintained in order to reduce erosion. Light weight plant materials with low water demand are recommended. Mesembryanthemum (ice plant) is not recommended for slope planting.
Based on our investigation, we do not believe that a shallow grounckater table exists at the site. So water table wm encoun- ter2d i.2 any 0': the four test tre;lcln~S, chr deepest be,ir:G 5 L-‘eet,
and ~w2 do not an-,ici.p:.3te any major gr9mdwater reiatrd probievs, eitner during or after construction. However, it should be recognized that minor groundwater seepage problems may occur after developmznt of a site even where none were present befor? development. These are usually minor phenomena and are often the result of an aiteration of the perzfieability characteristics 04' the soil, an aiteration in drainage patterns and an increase ir! irrigation water. Based on the permeability characteristics of the soil and the anticipated usage GC the development, it is 011: opinion .i;13: ninor soepag2 prociexs md,y 1.: .; c u r a r; r a :I ,jc:.:
locations, It is further our opinion that tnese problems can be most effectively corrected on an individual basis if and when they develop.
Based on the findings of this study, we conclude that with respect to geotechnical aspects, the subject site is suitable for the proposed project provided the recommendations contained in this report are fully complied with.
There are, however, on-site conditions that will require special design considerations as described below.
The moist, loose, porous fill soils beneath the proposed struc- tures will require densification prior to construction. It is anticipated that the thicknesses of loose surficial soil will vary from about 1.5 to 4 feet.
.
SDS 7570 July li, 1985 Page 8
preconstruction cnnference: We recommend that a preconstruction conference be held at the site with the developer, civil engineer, contractor, and geotechnical engineer in attendance. Special soil handling and the grading plans can be discussed at that time.
Soecifications; We recommend that all earthwork be done in ac- cordance with the attached "Recommended Grading Specifications". San Dieguito Soils, IRC. ‘ should observe the grading and test cmpacted fiiis.
All special site preparation recommendations presented in this report will supercede those in the standard Recommended Grading Specifications. All embankments, structural fill and fill should be compacted to not less than 90 percent of the maximum laboratory density. UtiliQ trench backfill within 5 feet of th,z proposed structures and beneath asphalt pavements should be com- pacted to not less than 90 percent of its maximum dry density. The maximum dry density of each soil tyoe should be determined in accordance with A . . * &.A. '+ -' Ts: Metnods 1$57-73.
Demol'tion. Cle&a and Ga . During site preparation, all debrii and deleterious materials derived from demolition, clear- ing and grubbing operations should be legally disposed of off- site prior to grading. Any existing utilities that will not be utilized should be removed and properly capped at the property line. The depressions resulting from the above operation should be backfilled with soil that has been compacted to at least 90 percent relative compaction.
ina Pad Preoaration and Areas to Receive FiL Beneath all . .
areas to receive fill, structural loads, and areas to be paved, we recommend that the .loose near surface.soils be removed to firm natural ground. Firm natural ground is defined as natural in- place soils that has an in-situ density equal to or greater than 85% relative compaction. It is anticipated that the topsoil will be about 3 feet in depth. Soils may then be replaced in 6 to 8 inch lifts, and compacted to at least 90%. Further, we recommend that the loose soils in the exploratory backhoe trenches beneath
the structure be densified to at least 90%.
ral Extent for work Procea . The lateral extent of the above described removals shall include all materials within 3 ~. feet beyond the perimeter of the building.
*
SDS 7578 July 17, 1985 Page 9
Areas to be Paved, . All areas to be paved should have the grade soils densified to at least 90% relative compaction minimum depth of 12 inches.
sub- to a
Moisture Content of Fill Soils, . All fill soils placed should have moisture contents of at least two percent over optimum mois- ture content.
I- . . Any fill material to be imported on-site should consist of granular, non-expansive soil that contains no organic or deleterious materials. It should have sufficient cohesion to hold a vertical or near vertical cut for footing excavations. It should have at least 85% of the material passing the ?Ii.rober 4 sieve with no rocks or chur,ics iarger than l-1/2 inches, The import fill shou.',cl 'be approved b:j our ot~iLce prior to ii being de;i vered to the site.
Foundations and Floor Slab%
The following recommendations are provided for construction on highly expansive soils.
a)
b)
cl
d)
e)
All footings should be founded a minimum of 24 below adj aca:t finish grade. Footings sho'tild minii:;u;o ibfidtil of 12 inches.
Both exterior and interior continuous footings be reinforced with two No. 4 bars positioned 3 should inches 4 bars above the bottom of the footings and two No. positioned l-1/2 inches clear below finish floor.
Interior slabs should be not less than 4.0 inches thick, underlain by a 4 inch blanketof clean sand or crushed rock, reinforced with 6"x6"-#6/#6 gauge wire mesh'or No. 3 bars spaced at 18 inches in both direc- tions placed at midpoint of the slab.
Exterior slabs should be a minimum of 4 inches in thickness and should be reinforced with 6"x6"-#lo/#10 welded wire mesh.
Clayey soils should not be allowed to dry before plac- ing concrete. They should be sprinkled if necessary to insure that the soils are kept in a very moist condi- tion or at a moisture content exceeding two percent above optimum moisture content. This condition should be carried to a depth of 24 inches below the bottom of the slab.
inches have a
SDS 7578 July 17, 1985 Page 10
f ) Weakened plane joints for exterior slabs should be provided for any slab greater than ten feet in width. Any slabs between 5 and 10 feet should be provided with a weakened plane joint at its center line. Slabs ex- ceeding 10 feet in width should be provided with a weakened plane joint located 3 feet inside the exterior perimeter. Both transverse and longitudinal weakened plane joints should be constructed. Please refer to Plate Number 9.
9) Surface drainage should be directed away from the proposed foundation. Planters should be constructed so that water is not allowed to seeu heneath foundations
OK slabs, Cver irrigation of are& *3djacer,t to founda- tions and slabs s2oulcl be avoic*d.
h) Prior to placing concrete, the foundation excavations should be inspected by a representative of this office to insure that the above recommendations have been followed.
We recommend that structures not able to tolerate differential settlements (such as foundations, concrete decks, walls, etc.; not be located withI: 7 feet or a slope top. We recommend that footings located within 7 feet from a siope top'be extended in depth until the outer bottom edge of the footings is at least 7 feet horizontally from the outside slope face.
lna Value, . An allowable soil bearing value of 1,300 pounds per square foot for spread footing foundations may be used for design of the on-site structures. In our opinion this value can be increased by up to one-third for loads that include wind or seismic forces.
Cut and Fm Slovea
It is our opinion that cut and fill slopes constructed from the native on-site materials will be stable with relation to deep- seated failures if constructed at or flatter than the following recommended slope ratios expressed in the horizontal to vertical units for the indicated heights:
Cut slopes 15 feet in height: 1.5:l Fill slopes to 20 feet in height 2:l
The above maximum heights were determined by using a factor of safety of 1.5.
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MY.
SDS 7578 July 17, 1985 Page 11
Fill slopes are susceptible to shallow sloughing in periods of rainfall or heavy irrigation. Sloughing of fill slopes can be reduced by backrolling slopes at frequent intervals. As a minimum, we recommend that fill slopes be backrolled at maximum cl-foot fill height intervals. Additionally, we recommend that all fill slopes be trackwalked so that a dozer track covers all surfaces at least twice.
Betainina Walls and Lateral Loads
The foundation for the proposed retaining structures should con- sist of spread footings founded in the firm nat,ivs soiis or com- pacted fill. Fir:2 natural groun,! ir; d!e:lr.ed a3 soii having an in-situ density of at ieast 85% 0: its maximum dry density, Footings may be designed for an allowable bearing pressure of 1300 psf. The bearing pressure may be increased to 4000 psf when the proposed footings are founded on the netavoicanic rock within the cut portion of the building pad.
We recommend that retaining walls not restrained from movement at
+$'-+ top and required to support lateral earth pressures due to 2-e erential soil height be designed f7r an equiv:x;ent fluid pressu,re of 65 pcf. In lieti of naxve material, imported clean sand or gravel may be used as backfill provided the natural material is sloped at an inclination of 1.5:1 from the bottom of the footing. Using this alternative, unrestrained walls should be designed for an equivalent fluid pressure of 35 psf; restrained walls should be designed for an equivalent fluid pressure of 45 psf. Retaining walls restrained from movement at the top, such as basement or structural walls, should be designed for an equivalent fluid pressure of 85 pcf where the on-site material is used as backfill behind the proposed retaining wall.
These pressures are based on horizontal ground surface conditions, and adequate drainage to prevent buildup of hydros- tatic pressure in the backfill.
To provide resistance for lateral loads, we recommend that pas- sive pressure be assumed equivalent to a fluid pressure of 255 pcf for footings and shear keys founded in cut formational soils or properly compacted clayey fill soils. For footings founded in formational metavolcanic rock, a fluid pressure of 400 pcf should be assumed. The upper 12 inches of material in areas not protected by floor slabs or pavements should be included in design for passive resistance to lateral loads. This lateral pressure is based on the assumption that the ground surface ad- jacent to the footing is nearly horizontal for a minimum distance
SDS 7578 July 17, 1985 Page 12
of 10 feet from the face of the footing or three times the height of the surface generating passive pressure, whichever is greater.
In calculation of frictional resistance to lateral loads, we recommend using a value of 0.0 as the allowable coefficient of sliding friction between concrete and the underlying soil when the footings are founded in clay. The calculation for frictional resistance to lateral loads, when footings are founded in metavolcanic material, a value of 0.4 as the allowable coeffi- cient of friction should be used.
Backfill placed behind walls should be compacted to not less than 90% of maximum dry density using light compaction equipment. heavy equipment is used, the walls should be appropriately braced. Expansive or clayey soils . should rot be used for I bat: fill material within a distance 0: 5 feet tram the back of tte
W&l. The retaining structure should not be backfilled until the materials in the wall have reached an adequate strength.
Pavement
The design of the pavement section was beycnd the scope of this investigation. However, the following recommendations are sub- mitted as preliminary guidelines for pavement construction.
After the site is graded and the subgrade soils are exposed in the parking and driveway areas, we recommend that these soils be sampled and tested so that pavement recommendations may be made.
The subgrade soils to a depth of at least 12 inches should be densified to at least 90%. Paved areas should be protected from moisture migrating under the pavement from adjacent water sources such as planted or landscaped areas. Saturation of the subbase soils could result in pavement failure.
The recommendations presented in this report are contingent upon our review of final plans and specifications. The soil engineer should review and verify the compliance of the final grading plan with this report.
.
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SDS 7570 July 17, 1985 Page 13
It is recommended that San Dieguito Soils, Inc., be retained to provide continuous soil engineering services during the earthwork operations. This is to observe compliance with the design concepts, specifications or recommendations and to allow design changes in the event that subsurface conditions differ from those anticipated prior to start of construction.
The recommendations and opinions expressed in this report reflect our best estimate of the project requirements based on an evalua- tion of the subsurface soil conditions encountered at the subsur- face exploration locations and the assumption that the soil con- ditions do not deviate appreciably from those encountered. It should be recognized that the performance of the foundations may be in2laenced by undisclosed oz unforeseen va:iatiocs in the soi.; conlicions that may occur in the intermr-ci:dzr in3 ur.ex?loreZ are22 . Ar:y i;;?us,ual conditions no- cc~?ied :.:I this report that may be encountered during site develcsment should be brought to the attention of the soil engineer so that he may make modifica- tions if necessary.
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,
The findings of this report are valid as of this date. Changes in the condition of a property can, however, occur with the pas- sage of time, whether they be due to natural processes or the work of man on this or adjacent properties. In addition, changes in the state-of-the-art and/or government codes may occur. Due to such changes, the findings of this report may be invalidated wholly or in part by changes beyond our control. Therefore, this report should not be relied upon after a period of two years without a review by us verifying the suitability, the conclusions, and recommendations.
In the performance of our professional services, we comply with that level of care and skill ordinarily exercised by members of our profession currently practicing under similar conditions and in the same locality. The client recognizes that subsurface con- ditions may vary from those encountered at the locations where our borings, surveys, and explorations are made, and that our data, interpretations and recommendations are based solely on the information obtained by us. We will be responsible for those data, interpretations and recommendations, but shall not be responsible for the interpretations by others of the information developed. Our services consist of professional consultation and observation only, and no warranty of any kind whatsoever, expressed or implied, is made or intended in connection with the
SDS 7578 July 17, 1985 Page 14
work performed or to be performed by us, or by our proposal for consulting or other services, or by our furnishing of oral or written reports or findings.
It is the responsibility of the owners, or their representative ‘to ensure that the information and recommendations contained herein are ~brought to the attention of the engineer and architect for the project and incorporated into the project’s- plans and specifications. It is further their responsibility to take the necessary measures to ensure that the contractor and his sub- contractors carry out such recommendations during construction.
SANDIEGUITOSOIIS,INC. VICINITY MAP
ky TSS JOB NO. 7578
DATE 7/17/e PLATE 1
_~
SAN DIEGUITO SOILS, INC. SITE PLAA
4407 MANCHESTER AVE., SUITE 107 BY T.S.S. JOB NO. 7578
. ENCINITAS, CA 92UZ4
,,, :-:, @‘*-7 DATE 7/S/85 PLATE 2
_.
UNIFIED SOIL CLASSIFICATION
I
MAJOR DIVISIONS GROUP SYMRc4 TYPICAL NAMES
FRACTION IS
LARGER THAN
NO. 4 SIEVE
SANOS
MORE THAN HALF
OF COARSE
FRACTION IS
SMALLER THAN
NO. 4 SIEVE
(LESS THAN
5% FINE.51
SILTS AND CLAYS
LID!,10 LIMIT IS
LESS THAN MX
SiLTS AND CLAYS
_ .._ -_
‘GW 1 sin-. WC,, graded gravel*. gravel-sad lnll,“,c*. lIttIe Of “.a
GP Poorly graded gravels 01 gravel-sand mixtures. little or 1 110 hnes.
GM 1 Silty giavels, gravel-*and-sill mixlures. non-plastic lines.
GC Clayey grwelr. gravel-sand-clay mi*wres. &tic finer.
SW Well graded sands. gravelly sands. little w IW finer.
SP Poo,,y graded sands p, gravelly sands. little or no fines.
SM Silty sandr. sand-sill mixtures. we-plastic fiis.
SC Clayey sands. sand-day mixtures. plasric lines.
ML lnor anic sdts and very line sands. !ock flour. silty or c ayey fine sjln*r or Cl.Yev IlllS wllh rhgh, PbSI!Cll”. s
CL Ire, 7 anic c,ayT 0, IOW 10 medium plaslicily, gra”eliV c av=.. sand” CIWS. Sill” cbis. Ican clays.. 1
OL log , d&C li,!T a-d orgaric sli:y ct.?ys of im plas:ic:l y /
__c--_----- _.-_I
c~mmucemis he sor’,ev 0,
.-i
LKIUIO LIMIT IS
GREATER THAN 50%
CH Inorganic clays 01 high plaslicily. fal clays. I
OH Ocganie clays of medium io high plaslicity, organic s;lis.
H!GHLY ORGANIC SOILS P: ! Peal and c,,her highly orgamc IO(,). i
U.S. ST+NOARD SER!ES SiEVE ----I----- CLEAR SCL’ARE S:EVE OPENikGS -
200 40 10 4 3/4” 3” ,Z”
SAND GRAVEL ~ SILTS AND CLAYS COBBLES BOULDERS FINE MEDIUM COARSE FINE COARSE
RELATIVE DENSITY CONSISTENCY
SANOS,GRAVELS PSJI BLOWS/FOOT Pqzt& ( STRENGTH 1 BLOWS/FOOT 1
VERY LOOSE
.MEOIUM DENSE
VERY DENSE
o- 4 VERY SOFT 0 - l/4 o-2
4 -10 SOFT l/4 - 1R 2-4
FIRM v2 - I 4-8 10 -33 STIFF 1 -2 6 -16
m-50 VERY STIFF 2 -4 16 -s2
CM350 HARD OVER 4 OVER 32
-g Water level at time of excavation or as indicated
on
Undisturbed driven ring or chunk sample
Disturbed bulk sample
SAN DIEGUITO $QIu, INC. SUBSURFACE EXPLORATION LEGEND
4407 MANCHESTER AVE., SUITE 107 By
ENUNITAS, GA 92024 TSS JOE NO. 7578
ml 7udso7 DATE 7/17/M PLATE 3
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rRENCH NUMBER 1
SLEVATION
OESCRIPTION
FILL: Brown silty/clayey medium sanh with meta- volcanic cobbles (6") and small roots
TOPSOIL: Brown fine sandy clay
SANTTAGO PEAK VOLCANIC: Gown metamorphosed tuff
Refusal
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dense
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SANDIEGU~~OSOILS,INC. SUBSURFACE EXPLORATION LOG
1 .4407 MANCHESTER AVE. SUITE 107 ,y ENCINITAS. CA 92024 TSS JOB NO. 7578
@W 7534@07 DATE 7/2/85 PLATE 4
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2
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1 -
2 -
3 -
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lRENCH NUMBER 2
ZLEVATION
DESCRIPTION
roPsoIL: 3rown medium sandy clay rith 6" metavolcanic :obbles
;ANTIAGO PEAK VOLCANICS 3rown metamorphosed :uff
Zefusal
ry
ry
stiff
very dense
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SAN DIEGUITO SOIIS, INC. SUBSURFACE EXPLORATION LOG
,447 MAIiCHESlER AVE.. SUllE 107 BY. JOB NO. TSS 7578
DAyE 7/2/85 PLATE 5
-
-
‘RENCH NUMBER 3
ELEVATION
DESCRIPTION
OPSOIL: rown medium sandy clay ,ith 6" metavolcahic obbles
ANTIAGO PEAK VOLCANICS ,rown metamorphosed tuf
:eEusal
SAN DIFGJTO SOILS, INC. 1 .4407 U&HESTER AVE., SUITE 107
..; fiNClNITAS, CA WO24
WI 753.8997
ry
dry
very stiff
very dense :I I 4 -f -,. -;
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SUBSURFACE EXPLORATION LOG I
BY .TSS _L. JOB Nt
DATE 712185 PLATE 6 I
: TRENCH NUMBER 4 .:* -: : ze z fwm ; y ELEVATION : & z i = a : ; 2 : : :o’g
OESCAIPTION 0 0 -- FILL: Brown silty/clayey oose
l :c medium sand with meta- volcanic cobbles (6")
2 - 1 -t
3 2 I!
4 -- - I__. TOP:O;;L: ------. i3row rlze'sandy clay tiff -.
5 -7 - -- _dS !*T
i SANilAGO PE4K ?OLCA:;T5: -- 7 Brown metamorphosed cry
6 - tuff 3 -i
Refusal 7
i + 1 1
’ i SAN DIEGUITO SOILS, INC.
107
SUBSURFACE EXPLORATION LOG
I
BY TSS 1 JOB N --- I O’ 7578
DATE 7/7/R5 1 PLATE 7
MAXIMUM DENSITY & OPTIMUM MOISTURE CONlEtiT
ASTM:
Maximum Sample Description Opt imum
Density Moisture IPCfl (XI
T-l @ 2.5' Brown ~fine sandy clay 115.5 15%
Def;cription a‘w!le .$f <c,%:,:ioll Int~5:nal
Friction I’! 13;fi ,l Int.:i’ca!:??
’
T-l @ 2.5' Brown fine sandy clay 25” 330
EXPANSION TEST RESULTS
Sample
:ONDlTlON
NITIAL MC. IX)
NITIAL DENSITY [pcfl
:INAL MC. [XI
YORMAL STRESS lpsfl
EXPANSION [Xl 10% 10%
T-2 @ 1 T-2 @ 1
Remolded Remolded
15% 15%
103.9 103.9
p SAN DIEGUITO SOIIS, INC.
4407 l4ANCHmER AVE., SUITE 107 ENCINITAS, CA B2024
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I LABORATORY TEST RESULTS
BY TSS JOB NO. 7578
DATE 7/17/85 MATE 8
TRANSVERSE
10’
SLAES IN EXCESS OF 10 FEET IN WIDTH
PLAN n.t.s.
SLASS 5 TO 10 FEET IN WICTH
tt
%“TO l/4”, JOINT SEALER
_. :.. ‘..>I.. .;. . ..s
ex6’-IO/IO w:, STliP J
IN ADDITION TO CON-,
TINUOUS REINFORCEMENT
DETAIL
n.t.s.
WEAKENED PLANE JOINT
SANDIEGUITOSOII.S,INC.
APPENDIX A
RECOMMENDED GRADING SPECIFICATIONS
Lienera Intenk
The intent of these specifications is to establish procedures for clearing, compacting natural ground, oreparing areas to be filled and placing and compacting fill soil to the lines and grades shown on the accepted plans. The recommendations contained in the preliminary soil investigation report are a part of the recommended grading specifications and shall supersede the provi- sions contained hereinafter in the case of confiic.:.
msoection and T?stinq
A qualified soil engineer shall be employed to observe and test the earthwork in accordance with these specificaticns. It wi1; be necessary that the soil engineer or his represerrtative provide adequate observations so that he may provide a memorandum that the work was or was not accomplished as specified. Deviations from these specifications will be permitted only upon written authorization from the soil engineer. It shall be the respon- sibility of the contractor to assist the soil engineer and to keep him appraised of work schedules, changes and new information and data so that he may provide the memorandum to the owner and governmental agency, as required.
If, in the opinion of the soil engineer, substandard conditions are encountered, such as questionable soil, poor moisture control, inadequate compaction, adverse weather, etc., the con- tractor shali stop construction until the conditions are remedied or corrected.
Unless otherwise specified, fill material shall be compacted by the contractor while at a moisture content near the optimum mois- ture content to a density that is not less than 90% of the maxi- mum dry density determined in accordance with A.S.T.M. Test No. D-1557-70, or other density test methods that will obtain equiv- alent results.
lng and mation of Areas to Receive Fill
All trees, brush, grass, and other objectionable material shall be collected, piled, and burned or otherwise disposed of by the contractor so as to leave the areas that have been cleared with a neat and finished appearance free from unsightly debris.
.
APPENDIX A (CONT'D)
RECOMMENDED GRADING SPECIFICATIONS
All vegetable matter and objectionable material shall be removed by the contractor from the surface upon which the fill is to be placed, and any loose or porous soils shall be removed or com- pacted to the depth determined by the soil engineer. The surface shall then be plowed or scarified to a minimum depth of 6 inches until the surface is free from uneven features that would tend to prevent uniform compaction by the equipment to be used.
When the slope of the natural ground receiving fill exceeds 20% (5 horizontal to 1 vertical), the original Ground shail oe stepped or jencned as s'nown on the attac'ne? Plate A. p,~n.:h;~:;
shall be cut to a firm compe,tent soil condirion. The Lower bench shall be at leas: 10 feet wide and all otiler benches at least 6 feet wide. Ground slopes fiatter than 20% &la11 be benched when considered necessary by the soil engineer.
&U Material
Materials for compacted fill shall consist of any material im- ported or excavated from the cut areas that, in the opinion of the soil engineer, is suitable for use in constructing fills. The materials shall contain no rocks or hard lumps greater than 12 inches in size and shall contain at least 40% of material smaller than l/4 inch in size. (Materials greater than 6 inches in size shall be placed by the contractor so that they are sur- rounded by compacted fines; no nesting of rocks shall be permitted.) No material of a perishable, spongy or otherwise im- proper nature shall be used in filling.
Material placed within 36 inches of rough grade shall be select material that contains no rocks or hard lumps greater than 7 inches in size and that swells less than 3% when compacted as hereinafter specified for compacted fill and soaked under an axial pressure of 150 psf.
Potentially expansive soils may be used in fills below a depth of 36 inches and shall be compacted at a moisture content greater than the optimum moisture content for the material.
Ucina. Swmdins and ComwactLna of Fill
Approved material shall be placed in areas prepared to receive fill in layers not to exceed six 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 to a minimum
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APPENDIX A (CONT'D)
RECOMMENDED GRADING SPECIFICATIONS
specified density with adequately sized equipment, either specifically designed for soil reliability. compaction or of proven Compaction shall be continuous over the entire area, and the equipment shall make sufficient trips to insure that the desired density has been obtained throughout the entire fill.
When the moisture content of the fill material is below that specified by tne soil engineer, th* fill material shall 3e aerated by the corltractor CT! blading, mi:::ing, or 0th.:: sat;s,ac- tory methods until the moisture concent is as specified.
The surface of fili slopes shall be cos:pacted and there shall be no excess loose soil on the slopes.
Observation and compaction tests shall be made by the soil en- gineer during the filling and compacting operations so that he can state his opinion that the fill was constructed in accordance with the specifications.
The soil engineer shall make field density tests in accordance with A.S.T.M. Test No. D-1556-70. Density tests shall be made in the compacted materials below tile surface where the surface is disturbed. When these tests i;,dicate that the density of any layer of fill or portion thereof is below the specified density, the particular layer portion shall be reworked until the specified density has been obtained.
The location and frequency of the tests shall be at the soil engineer's discretion. In general, the density tests will be made at an interval not exceeding two feet in vertical rise and/or 500 cubic yards of embankment.
During construction the contractor shall properly grade all ex- cavated surfaces to provide positive drainage and prevent ponding of water. He shall control surface water to avoid damage to ad- joining properties or to finished work on the site. The contrac- tor shall take remedial measures to prevent erosion of freshly graded areas and until such time as permanent drainage and ero- sion control features have been installed.
APPENDIX h (CONT'D)
RECOMMENDED GRADING SPECIFICATIONS
. * Unforeseen Condltlon
In the event that conditions are encountered during the site preparation and construction that were not encountered during the preliminary soil investigation, San Dieguito Soils, Inc., assumes no responsibility for conditions encountered which ~!iffer fro,:. those conditions found and described in the preliminary soil in- vestigation report.
Schematic only
net to scale
EXISTING GROUND SURFACE COMPACTED FILL
ZONE OF LOOSE
TOE KEY 2 FT. MIN.
INTO FIRM GROUND
HORIZONTAL BENCHES INTO
’ l ’
FIRM GROUND, 6 FT. MIN.
TOE KEY .WlDTH TO BE
DETERMINED BY SOIL ENGINEER,
BUT NOT LESS THAN 10 FT.
RECOMMENDATIONS FOR FILLING ON
SLOPING GROUND
SANDIEGUITOSOIIS,INC.
4407 MANCHESTER AVE. SUITE 107 BY JOB NO. . ENCINITAS. CA 92024 TSS 7578
-~:;,, WI 7538997 DATE 7/17/85 PLATE A