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HomeMy WebLinkAboutCT 82-04; PALOMAR OAKS II; SUPPLEMENTAL GEOTECHNICAL INVESTIGATION; 1988-04-26- REPORT Of SUPPLEJUTAL GEOTECHIIICAL IIIYESTIGATION PALCIIAR OMtS 11 BUSINESS PARK PAUlltJt AIRPORT ROAD CARLSUD, CALIFORIIIA PREPARED FCR: Bfrtcher Constructfon 27822 El Lazo Road Laguna Niguel, California 92656 PREPARED BY: Southern ~lffomfa Sofl I Testfng, Inc. Post Office Box 20627 6280 Riverdale Street Sin Diego. California 92120 / SOUTHERN CAL IF"ORNIA S OIL A N O TEST I NG , INC. 6 280 AIVEAOALE ST. SAN OIEGO. CALIF". 9 2120 • TELE 280 •4 321 P.O. SOX 20627 SAN OIEGO. CA LIF". 92120 6 7 8 EN 'fCQPA1 9 C 9 T CSCOND t DO C A Lt ,-9202~ • T£L I:. 7 46 •4 '-..&d April 26, 1988 Birtcher Construction 27822 E1 Lazo Road Laguna Niguel, California 92656 ATTENTION: Mr. Michael Dixon, Project superintendent SCs&T 8821057 Report No. l SUBJECT: Supplemental Geotechnical Investigation, Pal011ar oaks II Business Park, Palomar Airport Road, Carlsbad, California. REFERENCE: Preliminary Soils Engineering Investigation, Proposed Coaaercial Development, Ten Acre Parc!l, Carlsbad, California, dated January 5, 1982, by Action Engineering, Under Signature of Bruce A. Packard, RCE 13801. Gentlemen: In accordance with your request, we have performed a limited suppleaental investigation of the soil and geologic conditions at the subject site. The purpose of this investigation was to deteraine i f the soil and geologic conditions identified in a report oy Action Engineering were as stated and if their grading rec01111endations were adequate. We are presenting herei n a report of our findings. In general, we found that the majority of the subdivision is underlain by loose alluvial deposits in lieu of the bedrock identified in the Action S O U T HERN CALIF"ORNIA S O I L ANO T EST I NG . I N C . SCS&T 8821057 April 26, 1988 Page 2 Engineering report and that a substantial amount of site preparation work will be necessary. In addition, we found that a small landslide exists in the area of a proposed fifteen-foot-high cut slope and that a thick layer of soft colluvium exists where a .10-foot-high retaining wall is proposed. These conditions will al so require add·itional grading work. If you have any questions after reviewing the findings and recoaaendations contained in the attached report, please do not hesitate to contact our office. This opportunity to be of professional service is sincerely appreciated. Respectfully sumitted, SOUTHERN CALIFORNIA SOIL & TESTING, INC. a~ Charles H. Christian, R.G.E. #00215 CHC:JRH:• cc: (6) SUb111tted (1) SCSIT, Escondido TABLE Of CONTENTS PAGE Introduction and Project Description •••••••••••••••••••••••••••••••••••••• l findings •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 2 Sf te Descri ptf on •••••••••••••••••••••••••••••••••••••••••••••••••••.••• 2 General Geology and Subsurface Conditions ••••••••••••••••••••••••••••• 3 Geologic Setting and Soil Oescription •••••••••••••••••••••••••••• 3 Groundwater •••••••••••••••••••••••••••••••••••••••••••••••••••••• 5 Surface Water •••••••••••••••••••••••••••••••••••••••••••••••••••• 5 S1 ope Stabi 1 ; ty •••••••••••• , ••••••••••••••••••••••••••••• .! •••••••• 5 Conclusions ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 6 Rec011111endati ons ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 8 Site Preparatfon •••••••••••••••••••••••••••••••••••••••••••••••••••••• 8 Stream Diversion ••••••••••••••••••••••••••••••••••••••••••••••••• 8 Grubbing and Clearing •••••••••••••••••••••••••••••••••••••••••••• 9 Existing Fil 1 s ••••••••••••••••••••••••••••••••••••••••••••••••••• 9 Alluvial Soils ••••••••••••••••••••••••••••••••••••••••••••••••••• 9 Col 1 uvi u■ ••••••••••••••..•• , ••••••••••••••••••••••••••••••••••••• lU Landslide Debris •••••••••••••••••••••••••••••••••••••••••••••••• 11 ttewi Channel ••••••••••••••••••••••••••••••••••••••••••••••••••••• 11 Iaperfect Trench Backfill ••••••••••••••••••••••••••••••••••••••• 11 Select Grading •••••••••••••••••••••••••••••••••••••••••••••••••• 12 Earthwork ••••••••••••••••••••••••••••••••••••••••••••••••••••••• 12 S1 o·pe Stabi 1 i ty •••••••••••••••••••••••••••••••••••••••••••••••••••••• 12 Genera 1 ••••••••••••••••••••••••••••••••••••••••••••••••••••••.••• 12 South Slope for Lot Number 1 •••••••••••••••••••••••••••••••••••• 13 Channel Cut Slopes •••••••••••••••••••••••••••••••••••••••••••••• 13 Cut Slope Observation •.•••••••••••••••••••••••••••••••••••••••••• 13 Drainage •••••••••••••••••••••••••••••••••••••••••••••••••••••••• 13 Foundations and Slabs •••••••••••••••••••••••••••••••••••••••••••••••• 14 General Considerations •••••••••••••••••••••••••••••••••••••••••• 14 Footing Configuration ••••••••••••••••••••••••••••••••••••••••••• 14 Footing Reinforcing ••••••••••••••••••••••••••••••••••••••••••••• 14 Bearing Capacity ••••••••••••••••••••••••••••• -• •••••••••••••••••• 15 Foott ng Setback ••••••••••••••••••••••••••••••••••••••••••.••••••• 15 Interior Slaos •••••••••••••••••••••••••••••.•••••••••••••••••••• 15 - - - - TABLE OF CONTENTS (continued) PAGE Founda•ti on Pl an Review ••••...•••••..••..•••••••••••••••••••••••• 15 Retaining Wa 11 s ••••••••••.•••.•••.••••••••••••••••••••••••••••••••••• 15 General ••••••••••.••••••••••.••••••••••••••••••••••••••••••••••• 15 ATTACtllENTS FIGURE Figure 1 Site Vicinity Map, Follows Page 1 PLATES Plate 1 Plot Plan Plate 2 Cross-Section-AA Detail Plate 3 Cross-Section-BB Detail Plate 4 Cross-Section-CC Detail Plate 5 Cross-Section-DD Detail Plate 6 Unfffed So11 Classification Chart Plates 7-19 Trench Logs Plate 20 Stabilizing Fill at Section AA .Plate 21 Stabilizing Fill at Section BB APPENDIX Rec0111ended Grading Specifications and Special Provisions 5 SOUTHERN CALIF"ORNIA S OIL ANO TESTING . INC . 6280 ~IVE~OALE ST. SAN DIEGO. CALIF". 92120 • TELE 28 .J·_.3 2 1 P.O. BOX 20627 SAN DIEGO, CALIF". 92120 6 '7 8 C N f C ~ P A t S £ 5 T. £. S C D N C, I 0 o . C A L t r . 9 2 0 2 !> • T C L C: ? 4 6 • 4 5 .. 4 REPORT OF SUPPLEMEITAL GEOTECHNICAL INVESTIGATION PAL.<14AR OAKS II BUSINESS PARK PAL.<14AR AIRPORT ROAD CARLSBAD, CALIFORNIA INTROOUCTION AND PmJECT DESCRIPTION This report presents the results of a suppleaental investigation of the soil and geologic conditions at the site of a proposed eight lot business park, identified as Palomar Oaks II. The site is situated south of Paloaar Airport Road and about a mile-and-a-half east of Interstate 5, in the City of Carlsbad, California. The Paloaar Oaks I Subdivision lies to the east. The following vicinity map, Figure Number 1, illustrates the site location. The subject project consists of the subdivision of a ten acre parcel of land into seven c0111ercial/industrial lots and one open space lot (Lot 8) that will contain the easterly half of the new streu channel. Present plans call for completion of site grading, street improvements and channel i ■proveaents and then selling the 1 ots for i ndi vi dual or co■bined devel opaent. The mass grading will require about 37,000 cubic yards of i■port with another 12,000 cubic yards of fill obtained fr011 on-site cuts. Fills up to about 15 feet high are planned in the area of the channel and fills up to about nine feet high are planned for the lots. The nine feet of fill will be only on Lot l. The rest of the lots will have less than about five feet of fill placed on theta. Cuts will be li ■ited to a portion of the S OUTH ERN C AL IF O RNI A S O I L A NO TES T ING . INC . U-•• ·-· .. .,,.. ..... .., ·'-"•'-·•--·---~. ·•-· .. ~ ; :S.~.. :: .{:1=_; ---~=~·--------. --,. C) SOUTH CARLS8AO STAT£ 8UICH /''. ---~-....__ ... _=_--.....: -.,,,,. ATIOUITOS LAGOON ~;;.-:==~=-~--' l PALO!'.AR OAKS I I .£_ SOUTN ■IIN CALIPORNIA 'W SOIL a T■STING,INC. 1v: CHC/WDH DATE: JOI NUIIIEII: 882105 FIGURE ~l 7 SCS&T 8821057 April 26, 1988 Page 2 hillsi de skirting the south property and cuts to realign the stream channel. The maximu11 cut slope height is expected to be about fifteen feet high on the south side of Lot Number 1 and about 25 feet high in some areas along the new channel. Cut and fill slopes are planned at slope ratios of two horizontal to one vertical. The realignment of the stream channel will consist of the construction of both an open channel and a box culvert, with a drop structure on the downstream side of the culvert. Portions of the open channel wil 1 have a one quarter ton grouted rock slope protection. It is anticipated that the structures to be built on the site will be liai ted to one and two-story. tilt-up concrete structures wf th on-grade slabs and shallow spread footings. For the purpose of providing preliminary foundation recoanendations in this report, we assuad that wall loads will not exceed 3. 5 kips per 11 near foot and col wnn 1 oads wil 1 not exceed 80 kips. FINDINGS SITE DESCRIPTION The sabject site is an irregular shaped parcel of land located adjacent to and south of Pal011ar Airport Road and west of Paloaar Qaks Way in the City of Carlsbad. California. The site consists of approximately ten acres and is bounded by an undeveloped, north-facing hi 11 side on the south. undeveloped land on the west, and Pal011ar Qaks Way and coaercial property on the east. The site is comprised of an east-west trending valley with a well-incised stream channel. The stream chann~l is on the order of ten to t111enty feet wide and varies fr011 approxi11c1tely four feet to twelve feet in depth. The stream enters the site from the northeasterly corner and angles to the southern site boundary, and then traverses most of the site along the southern property boundary. The water w1 thin the s treaa ranges froa approximately six inches to two feet in depth. Topographically. the valley slopes toward the stream channel while the stream bed slopes very gently toward the west. Cut and fill slopes on the northerly and northeasterly portion of the site range up to approxiRliltely t111enty-five feet in height at 8 SCS&T 8821057 April 26 , 1988 Page 3 varying slope inclinations. Elevations range from approximately 140 feet (MSL) near the intersection of Palomar Airport Road and Paloaar Oaks Way to approximately 105 feet (MSL) near the southwesterly portion of the site. Drainage of the site is accomplished via sheetflow to the stream which flows to the west. In addition, the large, steep slopes off-site and adjacent to the southern property l ine, drai n into the stream via sheetflow and several wel i-incised drainage swales. Vegetation consists of a mixture of large trees, native shrubbery and dense native grasses and weeds. The approximate locations of a subsurface sewer main and water line and two sets of overhead, high-voltage power lines, which traverse the site, are shown on Plate Number 1. In addition, subsurface utility lines are located innediately adjacent to the northerly property line along Palomar Airport Road. GENERAL GEOLOGY MID SUBSURFACE CONDITIONS GEOLOGIC SETTING AND SOIL DESCRIPTION: The subject site is located in the Coastal Plains Physiographic Province of San Diego County and is underlain by Tertiary-age sedimentary deposits, Quaternary-aged 1 andslide debris, Quaternary-age alluvial/collluvial deposits, and artificial fill. Artificial fill with large amounts of asphalt, concrete and organic debris has been placed over much of the site. The approximate limits of the fill and debris are shown on Pl ate Number 1. Concrete debris as 1 arge as three feet in diameter was observed on the site. The fil 1 appears to ranye up t~ approximately eight feet in thickness and consists of a humid, loose, silty to clayey sand. In addition to the loose, debris-laden fill ooserved throughout 111Jch of the site, fill associated with the construction of Pal0111ar Airport Road and Palomar Oaks Way exists on the north, northeastern and eastern boundaries of the site. The thickest portions of these road fills a twenty-five-foot-high fill slope located at the northeast corner of the site. 9 SCS&T 8821057 April 26, 1988 Page 4 The alluvium, which exists throughout the entire valley floor, was found to extend to depths in excess of twelve feet below the existing ground surfa:e. Generally, the alluvium consists of friai>le silty sands, clayey sands, sandy clays and sandy silts. The alluvial deposits range from humid to saturated and loose to medium dense in consistency. Portions of the alluvium became wet at depths as shall ow as five feet and saturated at depths of approximately 9.5 feet below the existing ground surfaces. Colluvial deposits were encountered on the slopes located along the southern property 1 ine. Between the southern property boundary and the stream channel, colluvial deposits to depths ranging from approximately 10 feet to over 19.5 feet were encountered. The colluvium consists of humid to moist, soft to medium stiff and loose to medium dense, dark grey to dark greyish brown sandy clays and clayey sands. Clayey silts to silty clays, which appear to i>e older alluvium or landslide debris, were encountered underlying the colluvium in Trench Number 6. These soils were wet to saturated and soft to medium dense in consistency. In Trench Nullber 8, a loose, wet to saturated clayey to silty sandy alluvium was encountered underlying the colluvium. Landslide debris was encountered in Trench Number 4 at a depth between 2.5 feet to 8 feet below the existing ground surface. This debris ap~ears to be the lower portion of an old landslide that originated off-site and up-slope from the subject site. The approximate location of the la"dslide debris was derived froa viewing aerial photographs and a surface reconnaissance and is shown on Plate Number l. Dense and undisturbed fonnational soils were encountered at a depth of approximately 12.5 feet in Trench Number 4. The Tertiary-age Santiago Fonnation is the oldest soil unit on-site and underlies the alluvium, colluvium and artificial fill. The Santiago Formation is comprised of interlayered beds or layers of sandstones, siltstones and mudstones ranging from less than an inch to several feet in thickness. These soils are typically stiff to hard and dense in consistency and vary from a whitish light grey to yellowish brown and pale greenish tan. Portions of the Santiago Fonnat1on have relatively high strength lo SCS&T 8821057 April 26, 1988 Page 5 parameters while others, such as the mudstones and clayey siltstones, have relatively low strength parameters. Slope failures within the Santiago Formation have been identified in the slopes south and east of the subject site. Exposures of the fomatfonal soils were observed in the slopes on the northern portion of the site near Palomar Airport Road and were encountered at depths of approximately 4 feet and 7 feet below the existing grades in Trenches Number 11 and 10, respectively. GROUNDWATER: Groundwater was encountered in most of the excavation made fn the valley floor at depths ranging from approximately 9.5 feet to 14 feet below the ground surface. However, some soils became wet at depths as shallow as 5 feet from the adjacent ground surface. Grading operations for the removal and recompaction of loose alluvium may encounter water seepage and/or the groundwater table. Reconnendations to mitigate the potential groundwater problems are presented in the engfneerfng portion of thf s report. SURFACE WATER: Shallow, ponded surface water was observed on the northwesterly portion of the sf te. This appears to be due to trapped, precipitation run-off. Surface water flow was noted within the stream channel. This stream flows throughout the year and ranges from approximately six inches to two feet in depth at the present time. The area south of the subject site is comprised of a large, north facing il il 1 side with sever a 1 we 11 incised drainage swa 1 es, which drain onto the site. Drainage from thfs area south of the site will need to be taken into consideration when developing the subject site. SLOPE STABILITY: Landslide debris, which extends to a depth of approximately eight feet below the ground surface, was encountered in Trench Nullber 4 at the southeastern property boundary. The approximate limits of the landslide are shown on Plate Number l; the landslide is located primarily south of the subject site. No other slope failures either on-sf te or on the hill side imediately south of the sf te were identified from a surface reconnaissance and viewing aerial photographs. However, it should be recognized that several large, ancient landslides have been // identified in the north-facing slopes east of the subject site. SCS&T 8821057 Apri 1 26, 1988 Page 6 It should also be noted that the Santiago Formation is comprised of soils which exhibit both relatively high and relatively low strength parameters. This potential hazard for slope instability can be satisfactorily mitigated if the reco•endations regarding slope stability contained in the engineering portions of this report and proper slope maintenance techniques are fol lowed. All cut areas should be examined by a meaber of our geology staff during site grading operations to determine whether any adverse soil conditions are present and whether remedial actions are necessary. CONCLUSIONS Based on the results of our i nves ti gation. it is our opinion that the actual soil and geologic conditions at the subject site are substantially different than the con di ti ons identified by Action Engineering in their Preliminary Soils Report referenced herein. In particular, Action Engineering identifies "bedrock" or "sandy siltstones" and "silty sandstones" as existing at one to four feet below the valley floor, with one trench showing "bedrock" at a depth of seven feet. On the contrary, our subsurface explorations show that the valley contains a substantial aaount of loose alluvial deposits, as would be expected in a l:>road flat canyon with a relatively flat gradient. In addition, the site contains other geologic conditions not identified by Action Engineering that will have a substantial impact on grading. These include thick colluvial deposits on the south hill side where the retaining wall and cuts are planned and a landslide feature in the proposed cut area on Lot Number 1. It is our opinion, however, that the site can be developed as planned, provided the supp 1 ementa 1 rec011111endations presented herein are COIIP 1i ed with. Since the alluvial deposits are anticipated to be extremely deep and groundwater is relatively shallow, reaoval and compaction of this material is 110st likely not economically practical. Therefore, in order to develop the site, an alternate approach such as partial reaoval and stiffened foundation/slab systems was considered. However, it must be realized that some additional risks are inherent to such an alternative. SCS&T 8821057 AprH 26, 1988 Page 7 Since it would be economically impractical to remove all of the soft alluvial deposits at the site, we are providing below alternative site preparation reco11111endations that are intended to result in a site that can be developed with what we consider to be higher but 11reasonable risks•. In addition, it should be realized that our investigation was rather lillited in the amount of exploratory work perfonned, and therefore some of the soil conditions may differ from what we anticipate. Areas where we have only limited information at this time include the area where the culvert and new drainage channel is planned, the areas where the cut slopes on Lot 1 are planned and the area were the retaining wall on Lots 5 and 6 is planned. It should be understood that the actual site preparation needed in these areas may nave to be altered during grading from the recoaaendations provided herein if different soil and/or geologic conditions are uncovered. One approach would be to reaove as n1Jch of the alluvial soils above the water table as practical and, at the same time, provide a aat of c0111pacted fill under structures that would be thick enough to dissipate the foundation loads. In some areas, this may require removal below the present groundwater level and thus require some dewatering. Pimping the strea water around the site during grading may however 1 ower the present water table elevation enough to eliminate the need to dewater. Sf nee the locations of the buildings are not known, the lateral extent of the mat would need to cover a 1 most the entf re lot and should a 1 so include the street areas. Alternatives to the above could include only providing the compacted soil mat in building areas, but this requires knowledge of the building locations prior to grading. We understand that there is one plan in existence now that calls for five buildings on the seven lots and that this concept may be followed. If this is the case, shallower alluvial reaoval and thus a thinner mat of compaction could be allowed in the parking areas. This would SOlleWhat reduce gradfog costs. If the lots are to be sold and individually developed, a third option would be to grade the lots as if they were only parking lots by constructing a 13 SCS&T 8821057 ~ril 26, 1988 Page 8 mini~m c011pacted fill mat and requi ring the purchasers of the lots to regrade the building pads on the lots to establish the necessary compacted fill mat to dissipate building loads, or to use a deep foundation systetl such as driven piles. Since all the loose alluvium cannot be removed, s011e settlements will result fr011 the placement of fill above the existing grades. Al though we anticipate that most of this consolidation will occur during grading, ft is estimated that there will be some time dependent consolidation. With this in mind. settlement monuments should be placed at finish grade i-diately after grading is completed and they should be 111>nitored until it can be verified that only secondary consolidation potential remains. Further, the foundation and slabs for the buildings should be stiffened as rec0111ended herein to help resist distress due to this possible time dependent consolidation. Finally, ft should be realized that because of ti ■e restrains, our investigation for this project did not include deep borings or laboratory testing on soil samples. The conclusions and recoaendations contained herein are based solely on our experience at the adjacent subdivision to the east, which included deep borings and laboratory testing. and on our shallow subsurface explorations within the subject site. RECCNEl>ATIONS SITE PREPARATION STREM DIVERSION: The existing stream that traverses the site has year round flow. Due to the relatively flat gradient within the property, the water in the stream in some areas is as much as two feet deep. Because of the continuous fl ow, it wi 11 be necessary to divert the fl ow around the site during the grading and the construction of the new chinnel. This diversion may lower the groundwater table. out this is not expected to cause deeper removal of the allu1ium. . SCS&T 8821057 P.>ril 26, 1988 ?age 9 GRUBBING AND CLEARING: Vegetation within areas to ::>e graded should be re■oved and disposed of off-site. In exception to this, we understand that some of the large oak trees are to remain within the project. We realize that it is not possible to remove all vegetation fr011 grading projects. However. a 11 vegetation that is determined by the soil s engineer or his representative to be detrimental to structural fills aast be re110ved fr011 the site. My reaaining vegetation should be spread and mixed with the fill in a manner detenained by the sons engineer or his representative to be nondetriaental. In addition. all deleterious debris and trash that has been duaped on the site should be re■oved fr011 the site. In exception. any hard debris under t-..elve inches in diameter ma., be mixed and placed with fill. provided it is not placed within three feet of finish grade and it 1s placed in a manner that no nesting occurs. EXISTING FILLS: A relatively 1 arge a■ount of fill has been pl aced throughout the site. Although we understand that some of this fill may have been tested by Action Engineering, it is our opinion that all existing fill should be reaoved. An exception to this rec01111endat1on are the existing fills placed for Palomar Airport Road and Paloaar oaks Way that extend into the subject site. My fill material so re■oved that contains deleterious 11aterial in amounts detennined to be detriaental by the soils engineer or his representative should be removed fr0111 the site as discussed above. ALLUVIAL SOILS: To prepare the site to receive fill and structures. it is our recoaendation that the existing alluvial deposits be re■oved to one foot above the water table or saturation zone and be replaced as uniforaly CQllpacted fill. In buiiding pad areas. the re■oval depth should be such that there will be a mat of at least eight (8) feet of COllll)acted fill below finish pad grade. In parking areas and street areas. the re■oval should be such that there will be a mat of at least four feet of cQ11pacted fill below subgrade. Holllever, ft may be beneficial in areas where deep utilities such as sewers and storm drains are planned, be re■oved to a depth of two feet below the utilities. Ttiis will facilitate future trenching for the utilities by reducing the likelihood of cave-ins. SCS&T 8821057 .44>ril 26, 1988 Page 10 Groundwater and wet soils were generally encountered near the mini- removal depth recoillllended for building pads. However, diverting the stre111 water around the site may lower the water table by some undetermined amount. If saturated soils or soils that are too wet to work on are encountered at the recoiaended depth of reaova 1 , it may be necessary to stabilize the excavation prior to filling. This could be done in a nllllber of ways, one of which may consist of reaoving an additional two feet of soil and bridging t he excavation with two feet of dry soil, or by using crushed rock to stabilize the bottom. The minillUIII lateral extent of the re110val for building pads should include the area within five feet of the buildings. If the building locations are not known, then the entire pad within bu i l ding set back 11 nes, p 1 us five feet, should be assumed to be the building pad. We understand that saae of the 1 arge oak trees are to be saved. Since reaoving and rec011pacting the alluviu■ under the drip line of the trees cannot be done without possibly daaagi ng the trees, this wi 11 set the 11 mi ts of reaova 1 around trees. Wherever alluvium is left in place, buildings should be set back at least five feet. In addition to the trees that will limit removal and recoapaction. the existing se111er and water lines that cross the site and the poles and towr supporting the power lines will limit alluvium re■oval areas. Again. buildings must be set back at least five feet fr011 the edge of the reaoval li■its. The sewer amd water lines need to be well staked and extreme care should be taken by the grading contractor to protect these lines fro■ damage. COLLUVIUM: The hillside along the south side of the property is draped with a thick cap of 1 oose to medium dense colluviu■• This material should be prepared in the same manner as recomended above for the alluvial soils. Where these soils are exposed in cut slopes, the slopes will need to be stabilized a.s recomended in the slope stability section of this report. Where they will exist within the influence of the retaining wall footing to the south of Lots 5 and 6, they should be removed and be recompacted. Both SCS&T 8821057 ~ril 26, 1988 Page 11 the slope stabUization and the retaining wall suograde COlll)action will require some off-site grading. At the retaining wall south of Lots 5 and 6, the removal should extend at least five feet behi nd and in front of the retaining wall footing. The soils replaced should be granular soils. LANDSLIDE DEBRIS: Landslide involved soils were as identified on Lot 1 -.ere a cut slope is planned. Since this material is only soil that has spilled over the hil 1 side from a slide that occurred above the site and since the cut slope will not be cutting into or exposing the slide plane, this material can be treated as rec0111ended above for col luviu■• This includes stabilizing as recoanended i n the slope stability section of this report. NEW CHANNEL: The new a 11 gnaent of the channe 1 wil 1 resu 1 t in cuts made in various soil types including existing fills, alluvial and/or colluvial deposits and fonutional sandstones. As stated previously, we are not sure of the exact limits of these deposits since our trenching did not extend into this area. Wherever the cuts will expose the alluvial or colluvial soils, the slopes will need to be stabilized as recoaended in the slope staDiltty section of this report. Where cuts wil 1 expose existing fills, stabilization may or may not be required. These areas will need to be observed during cutting by our engineering geologist in order to determine if cuts into existing fills will need to be stabilized. I•ERFECT TREIICH BACKFILL: The soils report by Action Engineering refers to using "Imperfect Backfil 1" over the existing sewer 1 ines and we understand that this was i1111>leaented in the subdivision to the east. Section E on Sheet 2 of the grading plans shows a detail for the iaperfect backfill. Since the sewer lines will cross proposed parking areas and streets, and since the new fill over these lines wfl 1 be 1 ess than five feet and the sewer lines will be at a sufficient depth that it will not be affected by traffic loads, we are of the opinion that the imperfect backfill •thod should not be used. ti I SCS&T 8821057 April 26, 1988 Pag• 12 SaECT GRADING: In order to reduce the possibility of damage to structures and exterf or hardscape and pavements, we recc.:aend that the sf te be capped with at least three feet of nondetrimentally expansive soils. Nondetrfmental ly expansf ve soils are defined as soil with an expansive index of less that 50 as detennined by U.B.C. Test 29-2. Since about 37,000 cubic yards of soil will need to be imported to grade the site, we are not sure what soil types will be available for fill within the upper cap. If it is found that sufficient nondetrimentally soil is not available to cap the lots, special recoaendations for construction on expansive soils will be necessary. Such rec01111endations should be provided after the site grading is c011plete and it is known to what extent expansive soils may exist. EARlllfORK: All earthwork and grading contemplated for site preparation should be accomplished in accordance with the attached Recol'llllended Grading Specificatior.s and Special Provisions. All special site preparation rec0111endat1ons presented in the sections above will supersede those in the Standard Recoaended Grading Speciff cations. All eabankaents, structural fill and fill should be coapacted to at least 901 relative c011paction at or slightly over optillU■ moisture content. Utility trench backfill within five feet of the proposed structures and beneath asphalt pave•nts should be caapacted to a mini11U■ of 90S of its maxillUII dry density. The upper twelve inches of subgrade beneath paved areas shou 1 d be c011pacted to 95S of its maximum dry density. This c011pact1on should be obtained by the paving contractor just prior to placing the aggregate base material and should not be part of the mass grading requireaents. The maxillUII dry density of each soil type should be deten11ined in accordance with A.S. T.M. Test Method D-1557-78, Method A or C. SLOPE STABILin GENERAL: Cut and ffll slopes for the project are planned at a slope ratio of two horizontal to one vertical or flatter. The 111xi11U■ fill slope height will be about 20 feet adjacent the channel north of Lot 1 and about 10 feet between pads (at boundary between Lots 1 and 2). Maximum cut slopes will be about 25 feet in the channel north of Lot 3 and about 16 feet high on the le SCS&T 8821057 ~ri 1 26, 1988 Page 13 south side of Lot Number l. The fill slopes, as proposed, should have a factor of safety in excess of the minimum requirement of 1.5. However, some of the cut slopes will require stabilization to achieve this factor of safety. The slopes that will require stabilization are identified below. SOUTH SLOPE FOR LOT NUNBER 1: Two different adverse soil conditions exist fn the area of the proposed cut slopes on the south side of Lot Number l. These conditions include thick colluvium and landslide debris. However, for reasons discussed previously, the landslide debris may be treated like the colluvium. At the east end, near Trench Number 4, the colluvial soils and landslide debris should be removed and replaced with coapacted granular fill, as indicated on Plate Number 20. In the vicinity of Trench Number 1, the colluvium exposed in the slope should also be removed and be replaced with CQllpacted granular fill. Where the sandstones will not be encountered, a key at least five feet deep should be constructed at the toe. Plate NullDer 21 illustrates the configuration of this stabilizing fill. C CUT SLOPES: Cut slopes will be made in existing fills and possibly in alluvium and/or colluvium for the new channel north of Lots l through 3. If these cuts expose alluvial or colluvial soils, stabilizing fills similar to those 111 us trated on Pl ate Nuabers 20 and 21 wi 11 be necessary. Where only existing fills are exposed, they should be observed by a lllellber of our engineering geology staff to detennine to what extend, if any, the slope wil 1 need a stabilizing fill. CUT SLOPE OBSERVATION: All cut slopes constructed on the subject sf te should be observed by a 11e■ber of our engineering geology staff to detenaine if any geologic conditions are exposed that will adversely effect the stability of the slope. Should any adverse conditions be found, the appropriate mitigation reco-ndations will be provided. DRAINAGE: During heavy rains, a substantial a1110unt of drainage can f1o-,; down the hillside along the south side of the site. This drainage should not be allowed to flow over any cut slopes or stabilization fills. Further, the final 3rading and development should take this drainage into consideration. 19 • SCS&T 8821057 ~ri 1 26, 1988 Page 14 FOUNDATIONS AND SLABS GENERAL CONSIDERATIONS: As stated ear1ier, a stiffened foundation systell is necessary since some of the existing soft alluviu~ will remain undisturbed. Basically, this stiffening is obtained by inc-easing the size of footings and minimu■ reinforcing require111ents for footings under tfl t-up concrete walls, elillinating grade bea■ weakening "jogs" in perimeter footings, increasing the thickness and reinforcing of interior slabs, and tying the slai,s and footings together. We also recom■end that the top cord reinforcing steel of the tilt-up panels be at least two sizes larger than required by normal structural calculations. It should be recognized that due to the heterogeneous nature of the alluvial deposits and to possible time dependent consolidation produced by the fills, there is a slight risk of gt·C!ater than nonaal settlement of structures. However, it is our opinion that the risk of structural distress occurring that would jeopardize the structural integrity of buildings is relatively low. The recoaendations contained herein also assumes that the pads will be capped with soils that have an expansion index of 1 ess than 50. Based on these assuapti on!, the following recoaaendations are ~resented. FOOTING CONFIGURATION: All tilt-up concrete panels should be supported on a continuous grade beam foundation system. The grade beams should be at least 24 inches deep from top to bottom and should have a minillWI width of at least 18 inches. In order to provide continuity and strength to the grade beas, jogs in the grade beam should be eliminated. Isolated footings for interior co 1 umns should be. founded a mini 111.1m depth of 18 inches be 1 ow s 1 ao subgrade and should have a minimum width of 24 inches. FOOTING REIIFORCING: We recommend that all continuous footings and grade beams be reinforced with at least two No. 6 bars positioned near the top of the footing and two No. 6 bars positioned near the bottom. This reinforcing reccaaendatfon is based on the soil characteristics and is not intended to replace the reco1111endations of the structural engineer, where structural considerations are incorporated in the foundation design. SCS&T 8821057 April 26, 1988 Page 15 BEARING CAPACITY: Footings with the above reco11111ended mini~m dimensions can be considered to have an allowable soil bearing pressure of 2500 psf. This pressure may be increased by one-third for seismic and wind loading. FOOTING SETBACK: Where footings will ,un parallel with buried utility lines or structures, they should be positioned such that they will not l>e founded within the influence zone of the buried utility. This zone is usually defined as the trapezoidal shaped area above a 45 degree angle extending upward and away from the edge of the utility trench or structure. kty footings that need to be that need to be deepened to get below the zone of influence of the buried utility or structure may require special design as a result of an insufficient soil mat below the footing. Footings should also not be placed within five feet of the edge of the C0111Pacted fill mat rec0taended under "Site Preparation" herein. UITERIOR SLABS: Interfar slabs should have a mf nimu■ thickness of five inches and should be underlain by at least four inches of crushed rock or washed coarse sand. Where moisture sensitive floors are anticipated, the sand blanket should be covered with a layer of vi squeen and another two inches of washed sand. Interior slabs should be reinforced with No. 3 bars placed at 18 inches on center each way. FOUNDATION PLAN REVIEW: Foundation plans should be submitted to this office for review in order to detennine if the recoanendations contained herein are incorporated and to determine if any special reco•endations are necessary. RETAINING WALLS GENERAL: Although several walls are planned at the site, no reconaendations were provided in the Action Engineering report for retaining walls. It is our understanding that the concrete masonry walls have been designed using Standard Drawing C-2 of the City of Carlsbad. These standards are adequate for sandy formati ona 1 soils such as wil 1 exist in the area of the box culvert. At this tiae, we are not sure what soil conditions exist west and - SCS& T 8821057 April 26, 1988 Page 16 east of the proposed box culvert • .;pecific reco..endations can be provided for the walls in these areas if desired, however we will need to investigate what soil conditions will exist behind the walls before such reccaaendations can be provided. The proposed retaining wall on the south side of West Oaks Way (Lots 5 and 6) will be supported on CCJIIPICted fill. The fill should extend at least five feet behind the wall footing. This will leave room for a granular backf111 wide enough so that 111nimum 1 ateral pressures will be exerted on the wall. '3ee. lo..r5e. m4-p sec.,ti()" \ pl~-k':> I-5 SUBSURFACE EXPLORATION LEGEND UN!flED SOIL CLAS~IFICATION CHART SOIL DESCRIPTION GROUP SY"!90L I. COARSE GRAINED, more tnan nal f of materi al Is larger tnan llo. 200 sieve size. GRAVELS CLEAN GRAVELS GW ~an half of co,r~ fraction is largtr than No. 4 GP sieve size but saaller Ulan 3•. GRAVELS WITH FINES GM (Appreciaole amount of fines) GC SANOS CLEAN SANDS Nort°tllan hal f of SW SP coar~ fraction is suller tnan No. 4 sieve size. SANDS WITH FINES SM (Apprec iaDl e amount o! fines) SC JI. FINE GRAINED, mo~ tnan "-'lf of material is smaller ?"-'n No. 200 s i eve size. SILTS ANO CLAYS Ml Liquid Limit CL less than 50 !l. SILTS ANO CLAYS Iii Liquid Limit CH greater than SO OH HIGHLY ORGANIC SOILS PT Water level at time of excavation or as indicated US -Undisturbed, driven ring sample or tube sample IY: Well gradeC ;~avels, gravel- sand mixtures, l ittl e or no fi nes . Poorly graoed gravels, gravel sand mixtl.lres, little or no fines. Silty gravel s, poorly graded gravel-sand-silt mixtures. Clayey gravels, poorly graded gravel-sand, clay mixtures. Well gradeC sand , gravelly sands, li ttle or ro fines . Poorly gra~!~ sands. ;ravel ly sands, li ttle or no fines. Sil ty san~s. poorly graded sand and silty mixtures. Clayey sands, poorly graded sand and clay mixtures. Inorganic si l ts and very fine sands, rock flour, sandy silt or clay!y-silt-sand mixtures wiL~ slight plas-ticity. Inorganic clays of low to medium plasticity, gravelly cl1ys, s1nct1 cl1ys, silty cl1ys, lean cl1ys. Org1nic silts ind organic silty cl1ys or low plasticity. Inorganic silts, ■icaceous or diatomaceous fine sandy or silty soils, elastic Sil ts. Inorganic clays of high phsticity, fat clays. Organic clays of aediua to high plasticity. Pelt and other highly organic soils. CK -Undisturbed chunk sample BG -Bulk sample SP -Standard penetration sample Oaks I I JH DATI: 4-21-88 £. SOUTN■RN CALIFORNIA 'W SOIL a T■STING,INC. JOI NU Mal II : 8821057 Plate No. 6 -z "' 0 TRENCH NUMIEI ~ A. ;: 1 ► > ► () ► -► w .-► -► C z cc z z ► .. fl z -() .. 2 -~ IAI ::» IAI 11,1 en en C > :I: 1111 0 I&. ELEVATION C ► C ► z z -::» ► ► ► ~ C • • .. -► z ► u A. (I) -C .. ~ (I) IL 0 IL Q Q u • Ill C 2 (I) • ~ C l&l IL IL -0 ► ~ IL 0 C C C • C • C ► z Ill a en ~ 0 0 C • 0 C n u DESCRIPTION u 0 u 0 u -SM/ COLLUVIAM, Dark Brown, Humi d Loose to -SC CLAYEY SI LTY SAND, Porous 2-Humid/ Medium - I CK Moist Dense BAG -4_ Moist ---6. ---a. - CK - l ---12. - 14.. SC COLLUVIUM, Yellowish Tan to Moist f1edi um -Yellowish Brown, CLAYEY Dense -CK SAND -1 BAG ---l&_ - • CK Porous to very Porous --- ~ -Bottom - ---- -- -; - -- -- -- -- ~ SOUTN■IIN CALIPOIINIA .SUISUIFACE EXPLOIATION LOG SOIL A T■STING,INC. LOGGIDIY: JH DATE LOGGED: 4_12_88 Jo• Nu•n: 8821057 Plate No. 7 z --... 0 TRENCH NUMBER 2 ► ► ► -&. ► ► w ► u ► I-~ z -: ► z a: z z -Ill Ill 2 -► C en CIC --' u ... ~ .. ... en > a: ► II: ... z z -~ ... -... IU --ELEVATION z .. % 0 "' C cn C ! ... ... -.. u -' Q u ! Ill C C ► II. en -.. .. Q A .. en 0 • ... -' & 2 en .. .. 0 Ill 2 a C ► z ... a C C C C 0 C a II: Q en -' 0 Q 0 0 u OESCRIPTION u u u 0 -CL COLLUVIUM to 6.5', Dark GreJ Humid Soft - 1 -SAND CLAY Expansive ---2_ Humid / Medium Moist Stiff --- 3 Moist Stiff -Cl/ SUBSOIL, Dark Greenish Brown Moist Medium - 4_ SC SANDY CLAY to CLAYEY SAND Stiff with Caliche deposits -.. -s_ SC Expansive --- 6_ - 7_ Sf.1/ WEATHERED FORMATIONAL, Moist Medium SC Tan, SLIGHTLY CLAYEY Dense/ --SANDS Dense -. a_ - 9_ SM SANTIAGO FORMATION, Light Humid/ Dense/ Tan to Whitish Grey Moist Very - -Sli.TY SAND Dense - 10 --Bottom -- -- ------------ ~ SOUTH ■RN CALIPOIINIA SUISURFACE EXPLORATION LOG - LOGGED ■Y: JH DATE LOGGED: 4-12-88 SOIL a T■STING,INC. JOaNUMn: 8821057 Plate No. 8 - z ... 0 TRENCH NUMBER ► ~ .. ► 3 ... u ► ► ► "' ► ► -► C z a: z z ... ., ~ z ~ .J u "' co .. 2 :, Ill Ill ., & > z Ill --ELEVATION a: ... ... z z :, ... ... .J 0 ~ & ;: z -... en -C en C • Ill .., ... ... u .. .. en .. &. Q Q u • ., C C Ill a en ~ 0 ~ • ~ 0 ... .J .. Q C C C a C a a: ► z Ill a en .J 0 0 IIC a 0 a: 0 u DESCAIPTION u Q u 0 u -SC ALLUVIUM, Dark Grey and Mois t Loose 1 -Dark Brown, CLAYEY SANO ----2 -SM Yellowish Tan, SILTY SANO, Moist loose 3 Friable -----4 CK SC Mottled Dark Brown and Moist Loos e 5 Medium Brown Mixtu r e of - • BAG CLAYEY SILTY SANO and Moist/ SILTY CLAYEY SANO - • Wet -6 . -. -7 CK Wet -- 8---- 9---..I. Saturated ---10-. - -- 11 ---- 12 I -Bottom - -- -- ---- ~ SOUTN■RN CALIFORNIA .SUISUIFACE EXPLORATION LOG SOIL A T■STING,INC. LOGGIDaY: JH DATE LOGGED: 4_12_88 Joa Nu•n: 8821057 Plate No. 9 0 7 z ... 0 TRENCH NUMIER ► -'- Cl. I-4 I-u ► ► - -: ► "' I-► ~ z -I-C z C z z ► .. --.. 0 -... u "' :) "' "' en en C > % "' --ELEV ATION C ► z ~ ► ► 0 .. I-C z ; I-... Cl) - C Cl) C • ... "' ... z ► u Cl. Cl. Cl) Cl. IL 0 0 u • .. C C l&I 2 Cl) Cl. 0 Cl. • ..! 0 ► ... Cl. 0 C C C a C • C ► z "' a u, ... 0 0 C a 0 C 0 0 u DESCRIPTION u 0 u -u -CL TOPSOIL, Dark Grey to Dark Humid Soft 2 -Brown, SANDY CLAY - --Ml LANDSLIDE DEBRIS, Mottled 4 Yellow Tan to light Tan Moist Medium --SANDY CLAYEY SILT -:K SC/ -- Yellowish Tan to Light Tdn - 6 -BAG ML Moist Medium - CLAYEY SAND to CLAYEY SANDY Stiff/ SILT, more SANDY than soils -Medium -above 8 Dense - BAG SM COLLUVIUM , light Brown, Mo i s t loose/ 10 SILTY SAND, Slightly - CK Porous Medium Dense --SM WEATHERED FORMATIONAl light 12 Moist loose/ --Tan to Yellowish Tan SI LTY Medium -Cll~D " --· .,e -14 CK SANTIAGO FORMATION , light -Dense/ BAG Tan to Light Beige SILTY Very --SAND Dense -16 -- ----Bottom -- -- -- ---------------- ~ SOUTN■RN CALIPOIINIA suaSURFACE EXPLORATION LOG SOIL A T■STING,INC. LOGGaD8Y: JH DATE LOGGED: 4_12_88 JOaNu•n: 8821057 Plate No. 10 ~ z --"' 0 TRENCH NUMIER ► ► ► -A. ... a ... "' ► CJ ... >-tt. a -: ► z C z z .. .. g -... C Ill Ill en en C > -:, .. -~u C ... C ... z z -:, ► -► "' --ELEVATION z .. u :r: 0"' C • • ... -... ~ C IU Q u • ... C C ... A. cn -.. .. Q .!, A. cn .. 0 • -► ~ .. 2 cn a A. • C ► 0 z ... a Ill C C C C 0 C 2 C Q 0 0 0 .,, ~ u Q u n u OESCR I PTIO N u -SM/ ALLUVIUM, Medium Brown, Ory/ Loose SC CLAYEY to SILTY SANO Humid - 1-- CK - .. SM light Tan, SILTY SANO, Ory/ Loose - 3"' Porous Humid BAG -.. -4 SM Dark Brown, SLIGHTLY CLAYEY Humid/ Loose/ -BAG SILTY SANO, Porous and Moist Medium Col lapsable Dense -CK - " -----------------SC Mottled Yellowish Brown Moist Medium and Medium Brown, Cense -CK CLAYEY SAND to SILTY SANO ---8_ Wet ---9_ SM SILTY SANO Saturated -~ -1 -PB Ca vi ng at 1 O ' ---11 --Bottom -- -- ------ -- ♦ IOUTN■IIN CALIPOIINIA SUISURFACE EXPLORATION LOG LOGGaDaY: JH DATE LOGGID: 4-12-88 IOIL A T■ITING,INC. JOa NU-111: 8821057 Plate No. 11 '. "') - z -,,. 161 0 TRENCH NUMIER e ► ► ► -.. ► .. "' .. " .. .. -,,. z > C z a:: z z Ill Ill 0 -.. ., C -,J u "' ::I Ill Ill ., > ---a:: .. C .. z z -::I .. -.. z Ill 0 IL ELEVATION co IU -.. z .. u ,J C ., C Ill Q u • IU C .. A. ., -A. .. C ~ C A. ., 0 • 0 .. ,J .. 2 .,, A. .. a a C > z Ill a "' C C C C 0 C 2 C Q en ,J 0 Q 0 0 u DESCRIPTION u u u l, -SC/ COLLUVIUM to 10' Dark Humid Loose -CL Grey to Dark Grey Brown, 1-VERY SANDY CLAY to Moist Medium --VERY CLAYEY SAND, Dense - 2- Slightly Porous --- CK --BAG Caliche@ 4' to 5' ---- ,---SC Dark Brown, CLAYEY SANO Moi st Medium - 6- Expansive Dense - -- 7 CK -- 8---- ~ - -- 1n -Ml/ OLDER ALLUVIUM or LANDSLIDE "1oi st Soft/ - 1 CL DEBRIS, Mottled Yellowish Medium -CK Brown and Light Grey, Stiff VERY SANDY CLAYEY SILT to Wet - l BAG VERY SANDY SILTY CLAY Wet/ - Compressible C:;a t-u r;\ t-ori . -Bottom ------- - ~ IOUTN■IIN CALIFORNIA SUISURFACE EXPLORATION LOG IOIL A T■ITING,INC. LOGGEDH: JH DATE LOGGID:4_12_88 J08 NUll■111: 8821057 Plate No. 12 ~ 0 J1 z lit "' 0 ► ► TRENCH NUMBER 7 ► -A. ... ... "' ... u ... lit z ► z z ... Ill .. C a: z -2 -... "' Ill Cl) ., a: > -., u :, Ill a: ... a: ... z z :, ... ... % "' --ELEVATION ., Ill ;: ... z ... u ., 0 ~ C Cl) C -Ill Q u • Ill C ... A. Cl) -IL a. • Q " C A. Cl) IL 0 ... ., IL .... a Cl) a A. • a: ► 0 z Ill a C C C C a: a 0 0 0 0 a: 0 Cl) ., u Q u u OESCRIPTION (,) 0 -SC ALL UV I UM. Dark Brown, Moist Loose CLAYEY SAND - 1---.. 2---- 3 SM Light Reddish Brown, SI LTY Moist Loose -SAND - JI SC Dark Brown to Medium Brown Moist Loose/ J CLAYEY SAND, Compressible Medium -CK Dense ---6.. Tan ---7_ --- CK Medium Brown and Tan, Not Med ium - as Compressible as soils Dense -g_ above --- 1 CK Tan to Yellowish Ta n, Mais t/ - Mottled with Speckes of Wet - 11_ Yellowish and Tan soi ls from Wet/ SANTIAGO FORMATION Saturate j - -Bottom - ---- -- -- -- ~ SOUTN ■IIN CALIFORNIA .SUISUlfACE EXPLOIATION LOG SOIL a T■STING,INC. LOGGID ■Y: JH DATE LOGGED: 4-12-88 Joe Nu•n: 8821057 Plate No. 13 z ~ w 0 ► TRENCH NUMBER • ► ► -.. ... ... w ... (.) ... ... z -: ► z a: z z ... -w -.. 0 -C -► (.) !£i ::, w w r/) ., C > -~ a: ► C .... z z -::, ► -► z w ELEVATIO N (I) .. -.... z ► u 0 ~ C r/) C w ~ -0 u w C ... en .. 0 • C .. .. cn 0 .. • Q. 0 ► ~ .. a cn "' "' IE w a a: ► z • '" C C C C 0 C a C 0 0 0 0 en ~ u 0 u u DESCRIPTION u 0 -SCI COLLUVI UM to 12', Dark Grey Hum id Loose to CL Brown , SANDY CLAY to CLAYEY Moi st Soft - 2 t' 'llln -SC Dark Brown to Medi um Brown Moi st Medi um - 4_ VERY CLAYEY SAND Dense -BAG CK - 6-Grada ti ona 1 -Change 8 CK SC Medium Brown , CLAYEY SAND Moist Medium -Dense -- w E More SANDY t han soils above ; BAG occasional chun k of - indurated sand stone Moist/ -12 _ CK Wet SC ALLUVIUM, Medium Brown t o Wet Loose/ -Dark Brown CLAYEY SAND Saturate< Medium -14 ,, SC/ Dark Brown to Dark Grey Dense --SM CLAYEY TO SILTY SANO Loose --16 _ Minor roots and decayed -organics -ca ved-i n @ 13.5' -18 --Bottom ---- -- -- ---- ----~ -- ~ SOUTH■IIN CALIFORNIA SUISURFACE EXPLORATION LOG SOIL A T■STING,INC. LOGGED ■Y: JH DATE LOGGED: 4-13-88 JO• NUUE'II: Plate No. 14 8821057 z -~ "' 0 ► ► -TRENCH NUMBER • ► .. I-w I-0 I-I-~ z -: ► I-z z -11,1 -Ill 0 a: z -I-C w "' (I) (I) a: > -::, 11,1 -~ (.) a: ... C I-z z -::, I-I- % "' 0 I&. E L E V A TION C Cl) u, "' "' -I-z ~ u -' -C -0 u u, "' • C I-.. en (I) .. .. Gt 0 0. I-~ .. 2 en .. 0 .. -0 .. a K a: ► z Ill a Ill C C C C 0 a: a ac 0 0 0 0 en -' (.) 0 (.) 0 DESCRIP TION (.) (l SC FILL to 2.5', Da r k Brown and Hum id Loose -Light Tan t o Yellowish Tan, -SC/ 1-SM CLAYEY SAND and SI LTY SAND ---Concrete Debr is on ground - 2.. surface - --SM ALLUVIUM , Med ium Brown and Moi st Loose - BAG & Dark Yel lowi sh Brown -SC Interbedded SILTY SAND and - ~ CLAYEY SANO -CK Porou s 5.. SC/ Mott led Medium Brown, Moist Loose -SM CLAYEY SAND to SI LTY SAND -not as Porous as so il s - ~ abov e -CK 7_ SC Dark Brown to Dark Grey Moi st Medium -Brown, CLAYEY SANDS Dense --More CLAYEY than soils above -CK - i. - 11 SC Mottled Yel l owi sh Brown and Moist/ Loose/ -CK Medium Brown, CLAYEY SAND Wet Med ium Dense - 11 More Porous -than soi l s above ---12 Collapsabl e ---- 13 Bott om ------ ~ SOUTH■IIN CALIPOIIIIIA SUISUlfACE EXPLORATION LOG LOGGIDH: JH DATE LOGGl D: 4-13-88 SOIL A T■STING,INC. JOI NUll■ER: 882 1057 Pl ate No . 15 z l Ill 0 TRENCH NUMBER 10 ~ A. ► ► .... .... u ► - ► Ill ... ► -.... < z a: z z ... Ill ~ z -<J -Ill 0 -~ Ill :, Ill Ill Cl) c,, CIC Ill cc > % .J 0 14. ELEV ATIO N .... CIC .... z z -:» ► -... ► A. Cl) -C (I) C Cl) Ill "' -... z ... u A. Cl) A. A. Q 0 u Cl) Ill C C 2 II) A. 0 Cit ~ Ill A. ... .J Cl. 0 C C C a E CIC ► 0 z "' C a Cl) .J 0 0 cc a 0 CIC u DESCRIPTION u 0 0 0 <J c., -SC FILL, Medium Brown, CLAYEY Humid/ SAND _with Abundant Aspha]t Loose 1 -Dry - Debn s --- 2 -- 3 -SM/ ALLUVIUM to 7', Brown to Humid Loose/ SC Dark Brown, SILTY SAND Medium --to CLAY SAND Dense - 4 CK Porous -- 5 BAG --Roots@ 5' to 7' - 6 CK - - 7 Moist SM WEATHE~ED FORMATION, Mottled Moist/ -Medium 8 - Yellowi sh Tan to Li ght Tan Wet Den se/ - SILTY SAND ' Dense - K Roots @ 7' 9 to 8' - Very -BAG Dense -- 0 -Bottom - ----. -- -- -- -- -- -- ~ SOUTN■RN CALIFORNIA .SUBSURFACE EXPLORATION LOG SOIL & T■STING,INC. LOGGED IY: JH DATE LOGGED: 4_13_88 JOI NUIIIE'R: 8821057 Plate No. 16 . z ~ 11,1 0 ► 0. ;: TRENCH NUMBER 11 ... (.) ► ► -w ... ... ~ z -: ► z z ... Ill Ill -C a: z -0 -... -' ~ 11,1 ::, ... 11,1 en en a: > --a: ... z z -:, I--... % w 0 ~ ELEV A T IO N I-a: 1M -z ... (.) -' C en C en 1M ... ... en -0. -0 0 u • 1M C C 0. Cl) 0. Cit Q. 0. 2 en 0. 0 0. 0 ... -' .. 111 C C C a C I! a: > z 11,1 a 0 -' 0 0 a: s 0 a: 0 Cl) 0 0 CJ 0 0 DESCRIPTION (,) SM FILL, Light Ta~, SILTY Dry/ Loos e -SAND, Concrete Debris on Humid - 1 -ground surface - 2 BAG SM TOPSOIL, Dark Brown, SILTY Dry/ Loose SANO, with organic material Humid - 31 SC SUBSOIL, Dark Brown to Humid Medium CK Medium Brown , Expansi ve Dense - CLAYEY SAND - 4 Moi st -SC/ WEATHERED FORMATIONAL Moist Dense - 5 SM Mott led Light Ta n and Li ght CK Brown CLAYEY SAND - SM light Btige to Whitish Tan Humid / Very - 6 BAG SILTY, Fine Grained SAND Moi st Dense --Bottom -- -------- -- -------------------- ~ SOUTN■IIN CALIFORNIA SUBSURFACE EXPLORATION LOG SOIL A T■STING,INC. LOGGED ■Y: JH DATE LOGGED: 4_13_88 JOI NUIIIE'R: 8821057 Plate No. 17 z ~ Ill 0 TRENCH NUMBER ► ► L 12 I-(.) ► -I-Ill I-I-~ z -: ► z z ► ... -I-C C z -.. 0 -..J ~ Ill :, Ill Ill ., ., C > Ill C I-I-z z :, I--► % 0 u. ELEV A T ION C C • ... -► z ► (.) ..J Cl) C Ill I-~ Cl) -IL -0 0 u • .. C C ~ Cl) L • Q. a "' IL 0 IL 0 ► ... IL "' C C C a C R C ► z Ill • 0 Cl) ... 0 0 C • 0 C 0 f,J 0 u 0 <.> DESCRIPTION u SM FILL , Grey Brown SILTY SAND Dry Loose concrete ueor1 s 1 -SM & ALLUVIUM to 13' Ligh t Tan Dry/ Loos e --SC and Li ght Brown , Interbedded H!..lmid - 2 -SILTY SAND and CLAYEY SAND ---3_ Porous --Humid/ Moist -4_ ---5_ --- 6 -SC Dark Brown , CLAYEY SAND Humid / Loose/ -7_ Moist Medium Porous Moist Dense ---a_ ---9_ --- 10 CK SC Mottled Light Brown t o Tan Moist Loose/ -11 and Yellowish Tan, SLIGHTLY Medium -CLAYEY SILTY SAND We t Dense --- 12_ ~ Porous and Compress i ble -----13 --Bottom ---- ~ SOUTN ■IIN CALIFORNIA SUISUIFACE EXPLOIATION LOG SOIL & T■STING,INC. LOGGED ■Y: JH DATE LOGGED:4_13_88 JO• NUIIH11: 8821057 Plate No. 18 I z ~ "' 0 TRENCH NUMIEI ► ► -A, 11 ... () ► z ... Ill ... ... ~ -: ► z a:: z z ... ., -., 0 -... C Ill en a: -~ () ~ ... Ill en > --IIC ... a: ... z z -~ ... -... % ... 0 "' ELEVATION '° ... -... z ... CJ ~ C '° C Ill Q u Ill C ~ A, Cl) -.. .. Q ~ • C A, en 0 • .. ~ .. a Cl) .. .. -0 "' C C a C • a: ► z ... a 0 C 0 0 a: a 0 a: 0 Cl) ~ 0 <J <J CJ 0 DESCRIPTION <J -CL C0LLUVIUM, Dark Grey Brown Dry Soft - 2 -to Dark Grey, SANDY CLAY Humid/ Expansive Moist --Moist Medium - 4 Stiff CL/ Dark Brown, SANDY CLAY to Moist Medium -SC CLAYEY SAND with Caliche Stiff -I! 6_ Stringers -SC Medium Brown Medium -Dense -a_ -Slightly to Moderately -Porous -10 SC Mottled Yellowish Tan to Moist Medium -12 CK Yellowish Brown, CLAYEY Dense SAND - 14_ CK SM Mottled Pale Yellowish Ta ,1 Humid/ Loose/ SIL TY SAND Moist Medi um --Dense . - 16 CK Pnrnuc:: -Bottom ----- -- -- -- -- ------------ ♦ SOUTN■IIN CALIPORNIA SUISUIFACE EXPLOIATION LOG SOIL & T■STING,INC. LOGGIDaY: JH DATE LOGGED: 4_ 13_88 J08 NUMan: 8821057 Plate No. 19 ~~ lo.r5e. mCLp sec.. -fioh °vliiks ~o i:u PAL<ltAR OAKS II BUSINESS PARK. PAL<IWl AIRPORT ROAD. CARLSBAD RECOIIIEtl>ED GRADING SPECIFICATIONS -GENERAL PROVISIONS GENERAL INTENT The intent of these specifications is to estaolish procedures for clearing, c0111pacting natural ground, preparing areas to be filled, and placing and compacting fill soils to the lines and grades shown on the accepted plans. The recoanendations contained in the preliminary geotechnical investigation report and/or the attached Special Provisions are a part of the Reconnended Grading Specifications and shall sup~~sede 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 soil report or in other written conaunication signed by the Soil Engineer. • OBSERVATION AND TESTING Southern California Soil and Testing, Inc., shall be retained as the Soil Engineer to observe and test the earthwork in accordance with these specifications. It will be necessary that the Soil Engineer or his representative provide adequate observation so that he may provide an opinion that the work was or was not accomplished as specified. It shall be the responsibility of the contractor to assist the soil engineer and to keep him appraised of work schedules, changes and new infonnation and data so that he may provide these opinions. In the event that any unusual conditions not covered by the special provisions or preliminary soil report are encountered during the grading operations. the Soil Engineer shall be contacted for further recoaendations. If, in the opinion of the Soil Engineer, substandard conditions are encountered, such as; questionable or unsuitable soil, unacceptable (R-8/87) SCS&T 8821057 April 26, 1988 Appendix, page 2 moisture cortent, inadequate compaction, adverse weather, etc., construct1on should be stopped until the conditions are remedied or corrected or he shall reconnend rejection of this work . Test methods used to detennine the degree of compaction should be perfonned in accordance with the following American Society for Testing and Materials test methods: MaxillUII Density & Optinum Moisture Content -A.S.T.M. D-1557-78. Density of Soil In-Place -A.S.T.M. D-1556-64 ,or A.S.T.M. D-2922. All densities shall be expressed in terms of Relative Compaction as detet"llined by the foregoing A.S.T.M. testing procedures. PREPARATION OF AREAS TO RECEIVE FILL All vegetation. brush and debris derived shall be reaoved. and legally disposed of. from clearing operations Al 1 areas disturbed by site grading should be left in a neat and finished appearance, free fro■ unsightly debris. After clearing or benching. the natural ground in areas to be filled shall be scarified to a depth of 6 inches. brought to the proper moisture content. COlll)acted and tested for the mininum degree of c011paction in the Special Provisions or the recoaendation contained in the preliminary geotechnical investigation report. All loose soils in excess of 6 inches thick should be reaoved to firm natural ground which is defined as natural soils which possesses an in-situ density of at least 90i of its maxi ... dry density. When the slope of the natura 1 ground receiving f i 11 exceeds 20I ( 5 horizontal units to 1 vertical unit), the original ground shal 1 be stepped (R-8/87) SCS&T 8821057 April 26, 1988 Appendix, page 3 or benched. Benches shall be cut to a firm competent soil condition. The lower bench shall be at least 10 feet wide or 1 1/2 times the the equipment width which ever 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 oe compacted prior to receiving fill as specifie<I herein for compacted natural ground. Ground slopes flatter than 2ot shall be benched when considered necessary by the Soil Engineer. key 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 '!lith acceptable soil that is c0111pacted to the requirements of the Soil Engineer. This includes, but is not li ■ited to, septic tanks, fuel tanks, sewer lines or leach lines, ston1 drains and water lines. key buried structures or utilities not to be abandoned should be brought to the attention of the Soil Engineer so that he may detenaine if any special reconnendation will be necessary. All water wells which wi"ll oe abandoned should be backfilled and capped in accordance to the requirements set forth by the Soil Engineer. The top of the cap should be at least 4 feet below finish grade or 3 feet below the bott011 of footing whichever is greater. The type of cap will depend on the diameter of the well and should be detennined by the Soil Engineer and/or a qualified Structur~l Engineer. FILL MATERIAL Materials to be p1aced in the fill shall be approved by the Soil Engineer and shall be free of vegetable matter and other deleterious substances. Granular son shall contain sufficient fine material to fill the voids. (R-8/87) SCS&T 8821057 April 26, 1988 Appendix, page 4 The definition and disposition of overiized rocks, expansive and/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 material, but only with the explicit consent of the soil engineer. MY import material shall be approved by the Soil Engineer before being brought to the site. PLACING AND COMPACTION OF FILL Approved fill 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 a mini1111m specified degree of compaction with equipment of adequate size to econ011ically cOA1pact the layer. Compaction equipment should either be specifically designed for soil compaction or of proven reliability. The minimum degree of COllll)action to be achieved is specified in either the Special Provisions or the recommendations contained in the preliminary geotechnical investigation report. ,lhen the structural fill material includes rocks, no rocks will be allo-.ed to nest and all voids must be carefully filled with soil such that the mini1111m degree of compaction reconnended in the Special Provisions is achieved. The maximum size and spacing of rock permitted in structural fills and in non-structural fills is discussed in the geotechnical report, when applicable. Field observation and compaction tests to estimate the degree of c0111paction of the fill will be taken by the Soil Engineer or his representative. The location and frequency of the tests shall be at the Soil Engineer's (R-8/87) SCS&T 8821057 Apri 1 26 , 1988 Appendix, page 5 discretion. When t he compactfon test i miicates that a ;:,articular layer is less than the required degree of compaction. the layer shall be reworked to the satisfaction of the So i l Engineer and until the desired relative compaction has been obtained. Fill slopes shalt be compacted by means of sheepsfoot rollers or other suitable equipment. Compaction by sheepsfoot rol l ers shall be a~ vertical intervals of not greater than four feet. In addition, fill slopes at rati os of two horizontal to one vertical or flatter, should be trackrolled. Steeper fill slopes shall be over-built and cut-back to finish contours after the slope has been constructed. Slope compaction operations shall result i n all fill material six or more inches inward from t.he finished face of the slope having a relative compaction of at least 90S of maxi1111111 dry density or that speci fied in the Special Provisions section of this specificati on. The compaction operation on the slopes shall be continued until the Soil Engineer is of the opinion that the slopes will be stable in regards to surficial stability. Slope tests will be made by the Soils Engineer during construction of the slopes to detennine 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 co11111Unication from the Soil Engineer or his representative in the fonn of a daily field report. 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 Soils Engineer. (R-8/87) SCS&T 8821057 ¾>ril 26, 1988 ¾>pendi x, page 6 CUT SLOPES The Engineering Geologist shall inspect cut slopes excavated i n rock or lithified formational material during the grading operations at intervals determined at hi s 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 detennine if mitigating measures are necessary. Unless otherwise specified in the geotechnical report , no cut slopes shall be excavated higher or steeper than that allowed by the ordinances of the controlling governmental agency. ENGINEERING OBSERVATION Field observation by the Soil Engineer or his representat·ive 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. The presence of the Soil 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 speci fied degree of compaction. SEASON LIMITS Fill shall not be placed during unfavorable weather conditions. When work is interrupted by heavy rain, filling operations shall not be resu111ed until the proper moisture content and density of the fil 1 materials can be achieved. Damaged site conditions resulting from weather or acts of God shall be repaired before acceptance of work. (R-8/87) SCS&T 8821057 ~ril 26, 1988 ~pendix, page 7 RECCll4ENDED GRADING SPECIFICATIONS -SPECIAL PROVISIONS RELATIVE C<MPACTION: The minimum degree of compaction to be obtained in compacting natural ground, in the compacted fill. and in the compacted backfill shall be at least 90 percent. For street and parking lot subgrade, the ~pper six inches should be compacted to at least 95i relative compaction. EXPANSIVE SOILS: Detrimentally expansive soil f s defined as clayey soii 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 luaps of soil over 6 inches in diameter. Oversize materials should not be placed in fill unless recoaendations of placment of such 11aterial is provided by the soils engineer. At least 40 percent of the fill 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 mini1111■ of one foot below the base of the proposed footings and recOtlll)acted as stnictural backfil 1. In certain cases that would be addressed in the geotechnical report, special footing reinforceaent or a cOllbination of special footing reinforcement and undercutting may be required. (R-8/87) ~~ r · o· LEGEND so I v-LJ HINCH LOCATION ~=: ~::.~H SECTION Ocol ~LLUVIUN Olo OLLUVIUN To LANDI LID IANTIAOOII. FO -NEW •NATION CNANNIL AL,hNINT IOUTM CROii IICTION A•M NAU t'•t•· NORTN ..,,,,_OAUNINU .... ,., ....... ....... .... ,. .. 8 ,eo --------------------------------------------, "" 140t-------------------~-,A,,----------Ne•eu• ___ _1_·=----DMIC IIIOIIN, MEDIUM OHS[ I COLLUVIUN -1 ._ \ 1,0 i----------✓---,-,:-tt_:_:_=-~-All~T~--,... ~,:' ',-.."" COLLUVIUN, MEDIUM , ~ / ...._ FILL, LOOSE : >-,,-•" \ '~:t;--.... ---,---..,,-... -120 ..,..... __________ .....,, -""'11111'-------~--~-\...;----------- . : . -;--.. . ( ( C IOTTCIM OF TR~IICH Tl[IICH ' ~ • • , ., AT EL. 120.5 (NSL) IUllllt l ...... '" .-. ·. """"" -" .... .-:. -:-:.I, I • AT UlllllOIII ll(PTH , , ' .... -~ 80UTN ..,,.._ OMIPOIIHIA .... ,., ....... c•o•• 81CTIOII •-•· 1eM1 ,•.,e· ....... N.ATI •■ 120 ' efi1fftft\Eo,.!!IUM:;:_..:..111--4•I II OHS£ 110 ~lb':111°11h1M I -►----OHS[ · I -.; , . •' t ALLUVIIM,U,01r_'; "-1.i, .,.,:_ ~~_,..._._,_. __ ,,,,. ·: ~--lgSE~\ ~, ·.· ,_ ~ ,)..., -10() ·• IOTTON OF '•. ':' ✓. Tl[IIC~ AT EL • . ·. t 101.S (NSL) . · . ':,-. ...# TIEICN ·. . ... , t. IUIIU8 :· •• SANTIAGO FOIINATION ·' / •. • AT UIICIICM DEPTH •.::• .•. ":'-t / . . . ... ' 80UTN ... · · ·' ··.·.-:-:--, ..... / .... . . · c•o•• 81CTIOII C•C' MM.I t",te· LOOSE TO NEOIUM DENSE ALLUVIIM NORTN wn.-.oMP,Nll ...... , ....... ....... "-AT■•• D ft D .......... 1 " ...... ......... .---,.."-"'----IIM, LOOSE AND \"\~ 110 CDLLUVIIM,fit--.31-..,,,,---,-----A --- ,~j{IMrYf.NSE \""'--/" -~ '{ -t "( /~'" ALLUVIIJUOOSE 90 ~~--'/\. "'_:). ")--TO NEDIIM rYf.NSE -----4 _/ DLrYf.R ALLUVIIM OIi LAIIDSLID£ ~\ ~ ' ••ts, son TO NEDIIM STIFF ,. j-"" ·.•.7: .. ~t-;-,.J IOTTc,I OF TR(;~\ . eo • •" ' -Tlt(IICM ---AT (L. 96.S'i:.;MS:::L~\:.--------~ • • • It~ ' \ ·.: SANTIAliO FONTION • ••• ;: :' :~-, .1 _J L • AT UNOOIIII rYf.PTN : • , , • • •• -:, • f \ IOUTN . . . . ·. ·. :-: · t -\ ... ·. =--=---. . .. CIIOH IICTIOII D-0' ...... t'•••' ~ OAUPORIU .... , ............ ....... A A ,ea------------------------------------, .' • SMTIAliO ·.: •• '•. FOINTION , ' 80UT■. l■IIT•e eaae■ "······ ...... -·--- .. ~"' • • .. ..._ • i~ ..._ Fill ....... ,-,•.:--'--, 8TA■ILIZ1Ne PILL AT 8ICTION A-1' 1•aL1 r•t• •• ""-.......cOLLUVI"' NOIITN •· t«J·~---------------------~ .......... ll FILL, LOOS[ ,..._-~-----120L ______ _:::..,*~r-~~~~~r-~"t~~-:--------- IOUTN ...... ,, NOIITN SMTIMiO FONTIOII, -....: AT UlldOIII 0£,TH ....... ~ ITA■ILIZllle PILL AT IICTION I-■ MAU f'•te• ..... ., .......