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Home My WebLink AboutCT 13-06; LA COSTA VILLAS; GEOTECHNICAL REPORTS; 2014-11-17c-ct 3-.O( SMS GEOTEHNICAL SOLUTIONS, INcC, Consulting Geotechnical Engineers & Geologists 1645 S. Rancho Santa Fe Rd., Suit e208, San Marcos, Ca1brnia 92078 760-761-0799, srnsgeosoi. incgrnai1. corn Project No. GI-9-14-18 November 17, 2014 ACE Engineering Mr. Mike Massodnia 1645 South Rancho Santa Fe Road, Suite 208 San Marcos, California 92078 Southern Property Margins Hillside Toe Retaining Walls, Proposed La Costa Villas Development, Lot 401, Gibraltar Street At Jerez Court, Carlsbad, California (DWG 483-2A) cT I 3 - We have received and reviewed the most recent comments from the city of Carlsbad reviewer and the revised wall designs (by ANP Engineering dated, November 15, 2014) for the southern property margins hillside toe retaining wall with a sloping backfill condition, proposed in connection with the project development. Based on our review and from a geotechnical point of view the following are appropriate: An active lateral earth pressure of 50 pef (EFP) should be considered for the sloping rear hillside condition behind the wall underlain by undisturbed sedimentary formational rocks (Td), as now used in the revised wall designs. A seismic lateral inverted triangular earth pressure of 15H acting at 0.6H (His the retained above the base of the wall is acceptable to us andmay be considered as recommend by Allied Earth Technology (Page 10 of report dated June , 014, Project No. 13-1147H 1). It is noteworthy that the subject rear hillside toe retaining walls are site retaining walls (nod maximum. rocnjLs (Td). An allowable bearing pressure of 2000 psf be used for undisturbed competent formational rocks as specified in our report (Project No. GI-9-14-18), dated September 9, 2014. The net allowable bearing pressure can also be increased for additional foot of depth(s) and width(s), and by ½ for short term wind and seismic loading to the maximum designated value, as specified. Rear wall backcut excavations into the ascending hillside will exnose natural Page 1 of 2 - RECEIVED DEC 112014 Lii' __-i ENGINEER ItW 1 the lateral active soil pressure determination. Additional excavations into the ascending hillside for replacing the natural and competent siltstone/sandstone formational rock exposures within the wall active zone with select sandy ianuIar soilrtaante.d,.i We appreciate this opportunity to be of service to you. If you have any questions or need clarification, please do not hesitate to contact the undersigned. Reference to our Project No. GI-9- .14-18 will help to expedite our response to your inquiries. SMS Geotechnical solutions, Inc. o Distribution: Addressee (1. e-mail) MBM Development, Mr. Majid Mortazavi (2, e-mail) ANP Engineering, Mr. Pirouz Etemad(e-mail) CCH Design Group, Charles Heincy (e-mail) SMS GEOTECHMCAL SOLUTIONS, INC Page 2 of 2 SMS GEOTECHNICAL SOLUTIONS, INC. Consulting Geotechnical Engineers & Geologists 16455. Rancho Santa Fe Rd., Suite 208, San Marcos, California 92078 760-761-0799, srnsgeosol. inc- ginail corn Project No. GI-9-14-18 October 16,2014 ACE Engineering Mr. Mike Massodnia 1645 South Rancho Santa Fe Road, Suite 208 San Marcos, California 92078 Geotechnical Grading Plan Review And Response to City Review, Proposed La Costa Villas Development, Lot 401, Gibraltar Street At Jerez Court, Carlsbad, California (DWG 483-2A) We have received and reviewed the most recent Grading Plans for the proposed 8-unit La Costa Villas development at the above-referenced Lot 401 (DWG-483-2A). We have also received and reviewed the City of Carlsbad review comments of our report entitled "Addendum Geotechnical Plan Review Update, Proposed La Costa Villas Development, Gibraltar Street At Jerez Court Carlsbad, California," Project No. GI-9-14-18, dated September 9, 2014. The purpose of this effort was to review the project grading plans for Lot 401 (DWG-483-2A) from a geotechnical engineering viewpoint, and provide further information and/or clarifications to the S review comments raised by the City of Carlsbad. Based on our review, the following review comments, clarifications and additional information are appropriate: Grading Plan Review Based on our review, the project most current grading plans present a feasible design and is considered acceptable from a geotechnical viewpoint. All site development, grading and earthwork recommendations presented in the project soils and geotechnical reports (see report dated September 9, 2014 for a list of pertinent reports and documents) remain valid and should be considered in the project designs and implemented during the construction phase except where amended or superseded below. Response to The City Comments eralwe agree with the city reviewer regarding the total overall wall heights. The referenced report (dated September 9, 2014) refers to the exposed (above ground) wall heights, while the city reviewer considers the total wall height including the embedded portions below Page 1 of 2 the ground surface necessary to satisfy minimum setback requirements to daylight (sloping down ground conditions at the toe) he embedded wall portion may be considered in designs cj1gc. Alternative design methods may considered the embedded wall portion as a part of wall foundations receiving reduced active pressures below the ground surface and full active pressures above the ground surface in conjunction with reduced bearing pressure and reduced passive resistance due to sloping down ground surface at the toe of the wall. Considering the wall des RM wall heights for should be considered as faces, as indicated b III. LIMITATIONS This geotechnical plan review is not a "Plan Check Review" and does not relieve the responsibility of the project design consultant(s) and contractor(s) to get completely familiarized with the requirements of the project soil report(s) and fully incorporate its recommendations into the project design, plans and construction works, where appropriate, and as applicable. Our review and comments are for general geotechnical conformance of the project plans with the intent of the project soil report and design recommendations. Review of structural and civil engineering calculations, architectural intent and structural and civil engineering design modeling and basis, verification of set back requirements, easements and right-of-ways, as well as code, city and county compliance are beyond geotechnical engineering services. It is the owner's or his (her) representative's responsibility to provided copies of all pertinent soil report(s), updates, addendum letters and plan review letters to respective design consultant(s), and general contractor and his (her) subcontractor(s) for full compliance. We appreciate this opportunity to be of service to you. If you have any questions or need clarification, please do not hesitate to contact the undersigned. Reference to our Project No. 61-9- 14-18 will help to expedite our response to your inquiries. ii) ANP Engineering, Mr. Pirouz Etemad (e-mail; SMS GEOTECHNICAL SOLUTIONS, INC Page 2 of 2 SMS GEO TECHNICAL SOLUTIONS, INC. Consulting Geotechnical Engineers & Geologists Value Engineering 1645 S. Rancho Santa Fe Road, Suite 208, San Marcos, California 92078 Office: 760-761-0799 Cell: 760-331-8738 srnsgeosoi inc@grnaiL corn Project No. GI-9-14-18 September 9, 2014 ACE Engineering Mr. Mike Massodnia 1645 South Rancho Santa Fe Road, Suite 208 San Marcos, California 92078 Addendum Geotechnical Plan Review Update, Proposed La Costa Villas Development, Gibraltar Street At Jerez Court, Carlsbad, California Pursuant to your request, SMS Geotechnical Solutions, Inc. has completed the following Addendum Geotechnical Plan Review Update report for the proposed La Costa Villas development at the above- referenced property. This letter also serves as our verification that SMS Geotechnical Solutions, Inc is now retained as the Geotechnical Engineer of Record iiidigned has prior work history on the project while employed at Vinje & Middleton Engineering, Inc. in 2004, as noted in the references below. The project property is also designated as Lots 399,400 and 401 of La Costa South Unit No. 5. The approximate site coordinates are 33.086°N latitude and -117.2475°W longitude. Project development Plans are available and were reviewed as a part of this effort. Surface and subsurface geotechnical conditions at the project property were previously studied by prior consultants who issued the following technical reports outlining their findings and recommendations: . 1. "Second Update of Preliminary geotechnical Investigation Update Report, Proposed Multi- Unit Attached Dwellings, Gibraltar Street at Jerez Court, La Costa, California," prepared by Allied Earth Technology, Project No. 13-1 147H1, dated June 5, 2014. . 2. "Update of Preliminary Geotechnical Investigation Update Report, Proposed Multi-Unit Attached Dwellings, Gibraltar Street at Jerez Court, La Costa, California," prepared by Allied Earth Technology, Project No. 13-1 147H1, dated October 10, 2013. 3. "Preliminary Geotechnical Investigation Update Report, Proposed Multi-Unit Attached Dwellings, Gibraltar Street at Jerez Court, La Costa, Carlsbad," prepared by Vinje & Middleton Engineering, Inc., Job #04-287-P, dated July 7, 2004. This report was completed under the engineering supervision of the undersigned while employed at the Vinje & Middleton Engineering, Inc. ACE Engineering Mr. Mike Massodnia September 9, 2014 Page 2 4. "Preliminary Soil and Geotechnical Investigation, Graded Hillside Property, Gibraltar Street Near Jerez Court, La Costa Area of Carlsbad, San Diego County, California," Prepared by MV Engineering, Inc., Job #1017-91, dated February 20, 1991. The referenced reports were reviewed in connection with this effort and copies can be provided upon request. Based on the project available plans and reports, Lot 399 is a cut lot underlain mostly by Terrace Deposits, while Lots 400 and 401 are transition lots with filled ground in the northern frontage areas and formational bedrock cut surfaces in the southern rear areas. The purpose of this transmittal was to review the referenced reports and confirm compatibility of the project most current Grading Plans with the site indicated geotechnical conditions. Revised and/or amended recommendations consistent with the attached plans, current applicable codes and engineering standards are also provided in the following sections, and will supplement or superseded those given in the referenced reports. Based on our review of the referenced reports and project grading plans, development of the project properties for multi-unit attached residential dwelling purposes, substantially as proposed, is feasible from a geotechnical viewpoint. Geotechnical conditions reported in the referenced reports remain unchanged. All conclusions and recommendations provided, in the referenced reports also remain valid and should be incorporated into the final designs and implemented during the construction phase except where specifically superseded or amended below. Based on our review of the project plans, the southern perimefr site retaining walls are on the order o16 feet high maximum, while north-south running site retaining walls separating individual pads along the east and west sides are minor features less than 3 feet high maximum. Building basethent type retaining walls, parallel and adjacent to the site perimeter retaining walls, are on the order of 10 feet high maximum, will replace slope conditions and enlarge terraced pads upon construction, where they occur. Adequate setback or deepened foimdations shall be required for all foundations constructed on or near the top of descending slopes to maintain minimum horizontal distances to daylight or adjacent slope face, as specified There should be a minimum of 7 feet or one-third of the slope height, whichever is. more, horizontal setback from the bottom outside edge of the footing to daylight. The temporary transition slopes will be removed and replaced with building basement type retaining walls during the course of project development. The recommended foundation setback requirement will also provide for a safe future temporary wall backcut excavation, necessary for the adjacent lower building wall construction. S S S ACE Engineering Mr. Mike Massodnia • September 9, 2014 • Page S 3 Based on our review of the project plans, the upper site retaining walls (3 feet high maximum) appear to maintain adequate set backs with sufficient embedment depths avoiding . surcharging of the lower building basement type retaining walls. In general, a downward projected 1:1 line from edge of the upper wall foundations should not intercept the lower building basement type wall. 4. The following soil design parameters are based on the available strength tests completed by others on representative samples ofonsite earth deposits and our review of referenced reports: * Design active soil pressure for retaining structures = 35 pcf (EFP), level backfill, cantilever, unrestrained walls. * Design active soil pressure for retaining structures = 50 pcf (EFP), 2:1 sloping backfill, cantilever, unrestrained walls. * Design at-rest soil pressure for retaining structures = 53 pcf (EFP), non-yielding, restrained walls. * Design passive soil resistance for retaining structures = 350 pcf (EFP), level surface at the toe, compacted fills, soil mass extends 10 feet or 3 times the height of the surface generating passive resistance. * Design passive soil pressure for retaining structures = 420 pcf (EFP), level surface at the toe, competent undisturbed bedrock, soil mass extends 10 feet or 3 times the height of the surface generating passive resistance. * Design coefficient of friction for concrete on compacted fills = 0.35. * Design coefficient of friction for concrete on competent undisturbed bedrock = 0.40. * Net allowable foundation pressure (minimum 12 inches wide embedded at least .12 inches into compacted fills) = 1500 psf. * Net allowable foundation pressure (minimum 12 inches embedded at least 12 inches into underlying competent undisturbed bedrock) = 2000 psf. Notes: An additional seismic force due to seismic increment of earth pressure should also be considered in the project wall designs for building walls with greater than 6-feet soil differential on each side or retaining walls 12 feet or taller, as appropriate. A seismic lateral inverted triangular earth pressure of 24 pcf (EFP) acting at 0.611 (H is the retained height) above the base of the wall should be considered, where applicable. The seismic lateral earth pressure should be considered in addition to the specified static earth and surcharge (due to nearby foundation) pressures. When combining passive pressure and frictional resistance, the passive component should be reduced by one-third. ACE Engineering Mr. Mike Massodnia September 9, 2014 Page 4 The net allowable foundation pressure provided herein, was determined for footings having a minimum width of 12 inches embedded at least 12 inches into the underlying compacted fills or competent undisturbed bedrock, as approved in the field. The indicated value may be increased by 20% for each additional foot of depth and 10% for each additional foot of width to a maximum of 3500 psf for compacted fills and 4500 psf for undisturbed competent bedrock, if needed. The allowable foundation pressures provided herein also apply to dead plus live loads and may be increased by one-third for wind and seismic loading. LIMITATIONS The conclusions and recommendations provided herein have been based on all available data obtained from the review of pertinent geotechnical documents as well as our experience with the soils and bedrock materials located in the general site areas. Of necessity we must assume a certain degree of continuity between available exploratory excavations and/or natural exposures reported bu previous consultants. It is necessary, therefore, that all observations, conclusions, and recommendations are verified during the grading operation. In the event discrepancies are noted, we should be contacted immediately so that an inspection can be made and additional recommendations issued ifrequired. The recommendations made in this report are applicable to the site at the time this report was prepared. It is the responsibility of the owner/developer to ensure that these recommendations are carried out in the field. It is almost impossible to predict with certainty the future performance of a property. The future behavior of the site is also dependent on numerous unpredictable variables, such as earthquakes, rainfall, and on-site drainage patterns. The firm of SMS Geotechnical Solutions, Inc., shall not be held responsible for changes to the physical conditions of the property such as addition of fill soils, added cut slopes, or changing drainage patterns which occur without our inspection or control. s) should be aware that the development of cracks in all concrete surfaces such pLoc çss. These features depend chiefly upon the condition of concrete and weather conditions at the ti ~eo construction and do not reflect detrimental ground movement. Hairline stucco cracks will often develop at window/door corners, and floor surface cracks up to ½-inch wide in 20 feet may develop as a result of normal concrete shrinkage peording to the American Concrete Instituç). - ACE Engineering Mr. Mike Massodnia September 9, 2014 Page 5 This report is issued with the understanding that the owner or his representative is responsible for ensuring that the information and recommendations are provided to the project architect/structural engineer so that they can be incorporated into the plans. Necessary steps shall be taken to ensure that the project general contractor and subcontractors carry out such recommendations during construction. The project geotechnical engineer should be provided the opportunity for a general review of the projects final design plans and specifications in order to ensure that the recommendations provided in this report are properly interpreted and implemented. The project geotechnical engineer should also be provided the opportunity to field verify the foundations prior to placing concrete. If the project soil engineer is not provided the opportunity of making these reviews, he can assume no responsibility for misinterpretation of his recommendations. This report should be considered valid for a period of one year and is subject to review by our firm following that time. In case of plan revisions including changes in the final pad size, graded embankments, actual building and improvement locations, lines and grades, and final elevations, this report should be reviewed and updated by this office for review comments and additional recommendations based on the plan changes, as appropriate. We appreciate this opportunity to be of service to you. If you have any questions or need clarification, please do not hesitate to contact the undersigned. Reference to our Project No. GI-9- 14-18 will help to expedite our response to your inquiries. SMS Geotechnical Solutions, Inc. S. No. 2885 Exp. 12/31114 Distribution: Addressee (2, e-mail) 4 or MBM Development, Mr. MajMortazavi (2, e-mail) ANP Engineering, Mr. Pirouz Etemad SMS GEOTECHNICAL SOLUTIONS, INC consulting Geotecknicul Engineers & Geologists VALUE ENGINEERING ALLIED EARTH TECHNOLOGY 7915 SILVERTON AVENUE, SUITE 317 SAN DIEGO, CALIFORNIA 92126 PH. (858) 586-1665 FAX (858) 586-1660 (619) 447-4747 ROBERT CHAN, P.E. SECOND UPDATE OF "PRELIMINARY GEOTECHNICAL INVESTIGATION UPDATE. REPORT PROPOSED MULTI-UNIT ATTACHED DWELLINGS GIBRALTAR STREET AT JEREZ COURT LA COSTA, CALIFORNIA FOR - ACE CIVIL ENGINEERING PROJECT NO. 13-1147111 JUNE 5, 2014 ALLIED EARTH TECHNOLOGY 7915 SILVERTON AVENUE, SUITE 317 SAN DIEGO, CALIFORNIA 92126 PH. (858) 586-1665 FAX (858) 586-1660 (619) 447-4747 ROBERT CHAN, P.E June 5, 2014 Ace Civil Engineering 7668 El Camino Real #104-463 Carlsbad, CA. 92009 Attn: Mr. Mike Massoodnia Subject: Project No. 13-1147111 Second Update of "Preliminary Geotechnical Investigation Update Report" Proposed Multi-Unit Attached Dwellings Gibraltar Street at Jerez Court La Costa, California Dear Mr. Massoodnia: In accordance with your request, we have performed geotechnical engineering services for subject property, more specifically referred to as being Lot Nos. 399 to 401, inclusive, La Costa South Unit No. 5, in the City of La Costa, State of California. The purpose of our work is to prepare an update report with current geotechnical recommendations for the site development as presently proposed. The scope of our work includes two visits to the site, and a review of the following plans and documents: Project No. 13-1 147H1 Ace Civil Engineering 06/05/14 Page 2 Gibraltar Street "Preliminary Soil and Geotechnical Investigation, Graded Hillside Project, Gibraltar Street near Jerez Court, La Costa area of Carlsbad, San Diego County, California" prepared by MV Engineering, Inc.,(Their Job #1017-91, dated February 20, 1991.) "Preliminary Geotechnical Investigation Update Report - Proposed Multi-Unit Attached Dwellings, Gibraltar Street at Jerez Court, La Costa, Carlsbad" prepared by MV Engineering, Inc. (Their Job #04-287P, dated July 7, 2004). "Update of Preliminary Geotechnical Investigation Update Report - Proposed Multi-Unit Attached Dwellings, Gibraltar Street at Jerez Court, La Costa, Carlsbad" prepared by Allied Earth Technology, dated October 10, 2013. "Site Grading Plan for La Costa Villas" prepared by ACE Civil. Engineering of Carlsbad, dated May 27, 2014. PROPOSED DEVELOPMENT It is our understanding that the site is to be developed to receive 26 townhomes units. Nine units each will be constructed on Lot Nos. 399 and 400; and eight units on Lot No. 401. The proposed structures will consist of two stories above a two-car garage, and will be' of wood-frame/stucco and slab-on-grade construction. FIELD INSPECTION Inspections of the property on September 24, October 7, 2013, and May 23,2014, indicate that the site was found to be generally of the same condition when rough grading was completed in the early part of 1970, with the following exception: A high combined cut/fill slope on the order of 70 feet in maximum was observed along the rear, south end of the property, ascending to the residential lots to the south. Project No. 13-1147H1 Ace Civil Engineering 06/05/14 Page 3 Gibraltar Street This combined cut/fill slope has a slope ratio of 1 'A: I (horizontal: vertical), with two drainage ditches at mid-height. This combined cut/fill slope has been in existence since the early 1970's. The upper portions of this slope, which are within the properties to south, are well maintained and in good condition. The lower portions of the existing high cut/fill slope , which are within subject property has suffered some erosion and sloughing, due to lack of maintenance over the decades. The erosion and sloughing were caused by overflow of surface runoff from the drainage ditches on the slope, which were had been filled with debris and vegetation. through the decades. A review of the subdivision grading plan indicates that Lot 399 consists of all cut or natural soils. Lot 400 is a "transition lot", with a maximum of 3 feet of fill soils along the front portion of the site. Lot 401 is also a "transition lot", with a maximum of 7 feet of fill soils along the front of the property. The fill soils encountered on the property site were derived locally, and consist of a mixture of light brown/light gray/dark brown sandy clay, clayey sands and silty sands. These soils pdsess low to high expansion potential (Expansion Index of 46 and 98). SITE GEOLOGY Reviews of California DMG open-file report 96-02 and CGS geologic map of the Oceanside quadrangle indicate that the property is underlain by two formations : the Project No. 13-1 147111 Ace Civil Engineering 06/05/14 Page 4 Gibraltar Street Santiago FormãtiOñ, and Quaternary terrace deposits per the Department of Mine and Geology report, or. Quaternary Old alluvium, per the California Geologic Survey map. Both types of Quaternary units are mapped equivalently. As described in open-file report 96-02, the Santiago Formation-is middle Eocene in age (approximately 49 to 45 million years old). It consists primarily ofifrne to, ediumgrained sandstoneinterbedded withsiltstonéand ciaystone, and localized (coarse-grained sandstone and conglomerate:, Bedding attitudes in the Santiago Formation generally dips westward 5 degrees. The terrace/ãlluviüm deposits are younger, late to middle Pleistocene (approximately 1.8 to I million years old). They are reddish brown, poorly bedded and poorly to moderately indurated sätidstonsi1tst6ñe and conglomerate. GEOLOGIC HAZARDS Earthquake Fault Rupture Hazard San Diego's tectonic setting includes north and northwest striking fault zones, the most prominent and active of which is the Rose Canyon Fault Zone. Other fault zones lie in eastern and northern San Diego County. Fault rupture hazard would affect a property if an active fault trace or traces traverse the property. The subject property lies approximately 7 miles east of the offshore Newport-Inglewood Rose Canyon fault zone and 20 miles east of the offshore Coronado Banks fault zone. The property is approximately 28 miles west of the F Project No. 13-11 471-11 Ace Civil Engineering 06/05/14 Page 5 Gibraltar Street Elsinore fault zone, 57 miles west of the San Jacinto fault zone, and 82 miles west of the San Andreas fault zone. The property is outside any State and City designated fault and fault hazard zones and is therefore not subject to a special fault investigation.. The Rose Canyon Fault Zone is capable of generating a 6.9 magtnitude earthquake. Even though direct ground rupture from faulting directly underneath the subject property is unlikely, the property will be subjected to considerable ground acceleration and shaking from an earthquake event along the nearby faults. The intensity of ground shaking is dependent on distance from faults, earthquake magnitude and duration, and seismic characteristics of foundation soils and bedrock. Soil Liquefaction It is our opinion that due to the relatively high density of the competent natural and compacted fill soils (after remedial grading recommended herein) prevalent at the site; the lack of near-surface groundwater and the grain size characteristics of the in-situ soils, the risk for seismically induced soil liquefaction is very low. FINDINGS, CONCLUSIONS AND RECOMMENDATIONS In general, we concur and agree with the findings, conclusions and recommen- dations presented in the above-mentioned Report and Update, and said findings, conclusions and recommendations are still valid and applicable for the proposed site development.. Project No. 13-1 147H1 Ace Civil Engineering 06/05/14 Page 6 Gibraltar Street The following addendum recommendations are made, however, as supplement to the recommendations presented in the subject Report and Update. If there are discrepancies, the addendum recommendations herein will prevail. Expansiveness of On-site Near Surface Soils 1. Some of the near-surface soils encountered on the site possess high expansion potential (Expansion Index = 98). Earthwork 2 The current grading plans for the project were reviewed The three building pads will remain in their current elevations. Prior to commencement of grading, it is recommended that the site be cleared and grubbed, and all debris and vegetation disposed of offsite. 3, It is recommended that existing fill soils along the front of Lot Nos. 400 and 401 be removed Maximum depths of fill on these lots are on the order of 3 to 7 feet. The bottom of the over-excavation should be inspected by our firm, and scarified to a depth of 12 inches. The removed soils should then be properly moistened, and uniformly recompacted to at least 90 percent of maximum dry density in accordance with A.S.T.M. D1557, until finished grade is achieved.. 4. For Lot No. 401, it is recommended that the upper soils below finished grade be scarified to a depth of 12 inches, properly moistened and uniformly to at least 90 percent of maximum dry density in accordance with ASTM D1557. All footings Project No. 13-1 147H1 Ace Civil Engineering 06/05/14 Page 7 Gibraltar Street are to be extended into the underlying competent formation soils or bedrock. 5 Since the maximum depth of fill soils on Lot No. 400 is only 3 feet, and extends over a relatively small area, it is recommended that the footings of the proposed structure be extended through the compacted fill soils at 1east12 inches into the underlying competent formational soils. The upper, surface and near-surface soils on the building pads had been subjected to weathering for decades. It is recommended that the natural soils on Lot Nos. 399 and 400 be scarified to a depth of 12 inches, properly moistened and uniformly compacted to at least 90 percent of maximum dry density, in order to provide adequate support to the concrete slab of the proposed structures. Repair of Surficial Slope Failure It is recommended that the soils loosened by the erosion and sloughing of the existing slope be removed. The building pads along the toe of the existing slope will be widened, excavating and removing the loosened soils. A retaining wall will also be constructed along the bottom of the existing, slope. As the' repair work progresses up the existing slope, benches will have to be provided. The interval and width of the benches required will be determined by our field personnel during the remedial grading. 9. The surface of the slope should be properly compacted with a sheepsfoot roller. Project No. 13-1147H I Ace Civil Engineering 06/05/14 Page 8 Gibraltar Street In order to further minimize the potential for future surficial slumping, it is recommended that the slope be planted with deep rooted ground cover and shrubs at 10 feet on center. cFoundatiôjIand Slab It is recommended that a safe allowable soil bearing value of-i-,500 pounds .per C square foot b'used in the design and checking of continuous or spread footings that are a minimum of 15 and 24 inches in minimum horizontal dimension, respectively, and are ethbedded at least 24ihches into the competent natural or compacted filled ground' The above safe allowable soil bearing value may be further increased by one third when considering wind and/or seismic forces The concrete slab for the proposed structures should be at least 4 V2 inches net in thickness, and be reinforced with a minimum of #3 rebars at 18 inches on center in both directions, placed at mid-height of concrete slab. The concrete slab should be underlain by 4 inches of clean sand and a vapor barrier in moisture sensitive areas. 13.. The continuous footings should be reinforced with a minimum of 4 #5 rebars; two rebars located near the top, and the other two rebars near the bottom of the footings. Isolated pier footings should be reinforced with 2 #5 rebars in both. Project No. 13-1147111 Ace Civil Engineering 06/05/14 Page 9 Gibraltar Street directions, placed near the bottom of the footings. Please note that the above slab and foundation reinforcements are based on soil characteristics only, and should be superceded by the requirements of the project architect or structural engineer. It is recommended that the moisture content of the subgrade soils beneath the proposed structures be maintained at approximately 120% of optimum moisture content. However, no flooding of the foundation soils is permitted immediately prior to the placement of concrete It is recommended that the foundation for the proposed structure be setback at least 7 feet back from the top of the fill slope. Foundations placed closer to the top of the slope than 7 feet should be deepened such that the outer edge of the footing along the bottom is at least 7 feet back from the face of slope at that level. For footings subject to lateral forces, such as those of a retaining wall, the above setback should be increased to 10 feet. It is further recommended that the foundation trench excavations be inspected by our firm prior to the placement of concrete. Any loose and/or unsuitable soils encothitered should be removed and/or replaced under our direction. Retaining Wall Design It is recommended that retaining walls be designed to withstand the pressure exerted by equivalent fluid weights given on the following page: Project No. 13-1147H1 Backfill Surface (horizontal : vertical) Level 2:1 1Y2:l Ace Civil Engineering Gibraltar Street 06/05/14 Page 10 Equivalent Fluid Pressure (pcf) 35 50 58 The above values assume that the retaining walls are unrestrained from movement, and have a granular backfill. For retaining walls restrained from movement at the top, such as basement retaining walls, an uniform horizontal pressure of 7H (where H is the height of the retaining wall in feet) should be applied in addition to the active pressures recommended above. All retaining walls should be supplied with a. backfill drainage system adequate to prevent the buildup of hydrostatic pressure. The subdrain should consist of one- inch gravel and a perforated pipe near the bottom of the retaining wall. The width of this subdrain should be at least 12 inches, and extend at least 2/3 height of the retaining wall. The subdrain should be enclosed in a geotextile fabric such as Mirafi 140N or. equal. Seismic Earth Pressure Seismic earth pressures can be taken as an inverted triangular distribution with a maximum pressure at the top equal to 15H pounds per square foot (with H being s. the height of the retained earth in feet. This pressure is in addition to the Static design wall load. The allowable passive pressure and bearing capacity can be Project No. 13-1 147H1 Ace Civil Engineering 06/05/14 Page 1 I Gibraltar Street increased by 1/3 in determining the stability of the wall. A factor-of-safety of 1.2 can be used in determining the stability of the retaining wall under seismic conditions. Lateral Loading To resist lateral loads, it is recommended that the pressure exerted by an equivalent fluid weight of 350 pcf be used for footings or shear keys poured neat against competent natural or compacted fill soils. The upper 12 inches of material in areas not protected by floor slabs or pavements should not be included in the design for passive resistance. This value assumes that the horizontal distance of the soil mass extends at least 10 feet or three times the height of the surface generating the passive pressure, whichever is greater. A coefficient of sliding friction of 0.35 may be used for cast-in-place concrete on competent natural or compacted fill soils. Footings can be designed to resist lateral loads by using a combination of sliding friction and passive resistance. The coefficient of friction should be applied to dead load forces only. All backfill soils behind the retaining wall should consist of soils having low expansion potential (Expansion Index <50), and be compacted at least 90 percent of maximum dry density. Seismic Coefficients The seismic design factors were determined in accordance with the 2010 Project No. 13-1 147H1 Ace Civil Engineering 06/05/14 Page 12 Gibraltar Street California Building Code, and presented below: Site Coordinates: Latitude = 33.0860 Longitude 117.2475 Site Class: = D Site Coefficient Fa = 1.040 Site Coefficient Fv = 1.565 Spectral Response Acceleration At Short Periods . Ss = 1.153 Spectral Response Acceleration At .1-second Period SI 0.435 Sms = FaSs = 1.200 Smi = FvS.1 = 0.681 Sds = 2/3*Sms = 0.800 Sdl = 2/3*Sm1 0.454 Preliminary Structural Pavement Section Design For preliminary design purposes, it is recornn ended that a structural pavement section of 3 inches of asphaltic concrete over 6 inches of Class II base material over compacted subgrade be used. The upper 8 inches of subgrade and base material should be compacted to at least 95 percent of maximum dry density. For PeC pavement sections, it is recommended that the pavement section be 5 '/2 inches in thickness, and be reinforced with #3 rebars at 18 inches on center in both directions, placed at mid-height of concrete slab. Control joints at 12-foot intervals should also be provided. p. Project No. 13-11471-11 Ace Civil Engineering 06/05114 Page 13 Gibraltar Street Utility Trench Backfill It is recommended that any backfill soils placed in utility trenches located within 5 feet of any improvements and deeper than 12 inches, or backfill placed in any trench located 5 feet out or more from a building and deeper than 5 feet, be compacted to at least 90 percent of maximum dry density. Surface Drainage and Lot Maintenance Adequate drainage control and proper maintenance of all drainage facilities are imperative to minimize infiltration of surface water into the underlying soil mass in order to reduce settlement potential and to minimize erosion. The building pad should have drainage swales which direct storm and excess irrigation water away from the structure and into the street gutters or other drainage facilities. No surface runoff should be allowed to pond adjacent to the foundation of structures. Concrete Flatwork It is recommended that concrete flatwork be 3 '/2 inches in thickness and reinforced with 6 x6-1 0/10 welded wire fabric placed at mid-height of slab. One- inch expansion joints should be provided at 15-f6ot intervals; with '/4 inch weakened plane contraction joints at 5-foot' ntervals. LIMITATIONS The opinions and recommendations presented in this report are based upon surficial observations and logical projections inferred from observed conditions and the assumption that the soil conditions do not deviate appreciably from those encountered Should conditions vary from, those presented herein be encountered during the developmental construction phase, this firm should be notified immediately so that a qualified soil engineer can inspect the site conditions and evaluate the potential effects and present recommendations. Project No. 13-1147H1 Ace Civil Engineering 06/05/14 Page 14 Gibraltar Street This report has been prepared in accordance with generally accepted standards of geotechmcal engineenng practice at the time of its preparation No other warranties, expressed or implied, are made as to the professional consultation and recommendations contained herein This report is provided for the exclusive use of the client or his Respectfully ALLIED EA TECF1N5JGY I. Preliminary Geotechnical Investigation Update Report Proposed Multi-Unit Attached Dwellings Gibralter Street at Jerez Court La Cost crcl 3a opy July 7, 2004 Prepared For: MR. ALVIN WASHINGTON 6479 Paseo Cerro Carlsbad, California 92009. Prepared By: VINJE & MIDDLETON ENGINEERING, INC. 2450 Vineyard Avenue, Suite 102 Escondido, California 92029 Job #04-287-P E & MIDDLETON ENGINEERING, INC. 2450 Vineyard Avenue Escondido, California 92029-1229 Job #04-287-P July 7, 2004 Mr. Alvin Washington 6479 Paseo Cerro Carlsbad, California 92009 Phone (760) 743-1214 Fa (760) 739-0343 PRELIMINARY GEOTECHNICAL INVESTIGATION UPDATE REPORT, PROPOSED MULTI- UNIT ATTACHED DWELLINGS, GIBRALTER STREET, JEREZ COURT, LA COSTA, CARLSBAD, CALIFORNIA Pursuant to your request, Vinje and Middleton Engineering, Inc., has completed the Preliminary Geotechnical Investigation Report for the subject site. The following update report summarizes results of our research and review of pertinent geotechnical reports and documents, current field reconnaissance, and provides conclusions and recommendations for the proposed development as understood. From a geotechnical engineering standpoint, it is our opinion that the site is suitable for the support of planned multi-unit development and associated improvements provided the recommendations presented in this report are incorporated into the design and construction of the project. The conclusions and recommendations provided in this study are consistent with the site geotechnical conditions and are intended to aid in preparation of final development plans - and allow more accurate estimates of development costs. If you have any questions or need clarification, p!ease do not hesitate to contact this office. Reference to our Job #04-287-P will help to expedite our response to your inquiries. We appreciate this opportunity to be of service to you. VINJE &MIDDLETON ENGINEERING, INC. ,Q 4i4 / 11%' CEG 980 Dennis Middleton * ( CERTIFIED I * CEG #980 t ' ENGINEERING I DMfjt II ii SAN DIEGO, CALIFORNIA 92126 PH. (858) 586-1665 FAX (858) 586-1660 (69)447-4747 ROBERT CHAN, P.E. SECOND UPDATE OF "PRELIMINARY GEOTECHNICAL INVESTIGATION UPDATE REPORT PROPOSED MULTI-UNIT ATTACHED DWELLINGS GIBRALTAR STREET AT JEREZ COURT LA COSTA, CALIFORNIA CT FOR ACE CIVIL ENGINEERING PROJECT NO. 13-1147H1 JUNE 5, 2014 PLAN C'EC( NOR, I ALLIED EARTH TECHNOLOGY 7915 SILVERTON AVENUE, SUITE 317 SAN DIEGO, CALIFORNIA 92126 PH. (858) 586-1665 FAX (858) 586-1660 (619) 447-4747 ROBERT CHAN, P.E. June 5, 2014 Ace Civil Engineering 7668 El Camino Real #104-463 Carlsbad, CA. 92009 Attn: Mr. Mike Massoodnia Subject: Project No. 13-1147141 Second Update of "Preliminary Geotechnical Investigation Update Report" Proposed Multi-Unit Attached Dwellings Gibraltar Street at Jerez Court La Costa, California Dear Mr. Massoodnia: In accordance with your request, we have performed geotechnical engineering services for subject property, more specifically referred to as being Lot Nos. 399 to 401, inclusive, La Costa South Unit No. 5, in the City of La Costa, State of California. The purpose of our work is to prepare an update report with current geotechnical recommendations for the site development as presently proposed. The scope of our work includes two visits to the site, and a review of the following plans and documents: I Project No. 13-1147H1 Ace Civil Engineering 06/05/14 Page 2 Gibraltar Street "Preliminary Soil and Geotechnical Investigation, Graded Hillside Project, Gibraltar Street near Jerez Court, La Costa area of Carlsbad, San Diego County, California" prepared by MV Engineering, Inc. (Their Job #1017-91, dated !February29.j99 L) "Preliminary Geotechnical Investigation Update Report - Proposed Multi-Unit Attached Dwellings, Gibraltar Street at Jerez Court, La Costa, Carlsbad" prepared by MV Engineering, Inc. (Their Job #04-287-P. dated July 7, 2004). "Update of Preliminary Geotechnical Investigation Update Report - Proposed Multi-Unit Attached Dwellings, Gibraltar Street at Jerez Court, La Costa, Carlsbad" prepared by Allied Earth Technology, dated October 10, 2013. "Site Grading Plan for La Costa Villas" prepared by ACE Civil Engineering of Carlsbad, dated May 27, 2014. PROPOSED DEVELOPMENT It is our understanding that the site is to be developed to receive 26 townhornes units. Nine units each will be constructed on Lot Nos. 399 and ZighLBRi6on Lot No. 401. The proposed structures will consist of two stories above a two-car garage, and will be of wood-frame/stucco and slab-on-grade construction. FIELD INSPECTION Inspections of the property on September 24, October 7, 2013, and May 23,2014, indicate that the site was found to be generally of the same condition when rough grading was completed in the early part oU7,Q2 with the following exception: A high combined cut/fill slope on the order of 70 feet in maximum was observed along the rear, south end of the property, ascending to the residential lots to the south. Project No. 13-1 147H1 Ace Civil Engineering 06/05/14 Page 3 Gibraltar Street This combined cut/fill slope has a slope ratio of 1 1/2: 1 (horizontal : vertical), with two drainage ditches at mid-height. This combined cut/fill slope has been in existence since the ear1y1970's. The upper portions of this slope, which are within the properties to south, are well maintained and in good condition. The lower portions of the existing high cut/fill slope , which are within subject property has suffered some erosion and sloughing, due to lack of maintenance over the decades. The erosion and sloughing were caused by Overflow of surface runoff from the drainage ditches on the slope, which were had been filled with debris and vegetation through the decades. A review of the subdivision grading plan indicates that Lot 399 consists of all cut or natural soils. Lot 400 is a "transition lot", with a maximum of 3 feet of fill soils along the front portion of the site. Lot 401 is also a "transition lot", with a maximum of 7 feet of fill soils along the front of the property. The fill soils encountered on the property site were derived locally, and consist of a mixture of light brown/light gray/dark brown sandy clay, clayey sands and silty sands. These soils possess low to high expansion potential (Expansion Index of 46 and 98). -d SITE GEOLOGY Reviews of California DMG open-file report 96-02 and CGS geologic map of the Oceanside quadrangle indicate that the property is underlain by two formations : the S S Project No. 13-1 147H1 Ace Civil Engineering 06/05/14 Page 4 Gibraltar Street Santiago Formation, and Quaternary terrace deposits per the Department of Mine and Geology report, or Quaternary Old alluvium, per the California Geologic Survey map. Both types of Quaternary units are mapped equivalently. As described in open-file report 96-02, the Santiago Formation is middle Eocene in age (approximately 49 to 45 million years old). It consists primarily of fine to medium-grained sandstone interbedded with siltstone and claystone, and localized coarse-grained sandstone and conglomerate. Bedding attitudes in the Santiago Formation generally dips westward 5 degrees. The terrace/alluvium deposits are younger, late to middle Pleistocene (approximately 1.8 to 1 million years old). They are reddish brown, poorly bedded and poorly to moderately indurated sandstone, siltstone and conglomerate. GEOLOGIC HAZARDS Earthquake Fault Rupture Hazard San Diego's tectonic setting includes north and northwest striking fault zones, the most prominent and active of which is the Rose Canyon Fault Zone. Other fault zones lie in eastern and northern San Diego County. Fault rupture hazard would affect a property if an active fault trace or traces traverse the property. The subject property lies approximately 7 miles east of the offshore Newport-Inglewood Rose Canyon fault zone and 20 miles east of the offshore Coronado Banks fault zone. The property is approximately 28 miles west of the S I Project No. 13-1 147H1 Ace Civil Engineering 06/05/14 Page 5 Gibraltar Street Elsinore fault zone, 57 miles west of the San Jacinto fault zone, and 82 miles west of the San Andreas fault zone. The property is outside any State and City designated fault and fault hazard zones and is therefore not subject to a special fault investigation. The Rose Canyon Fault Zone is capable of generating a 6.9 magnitude earthquake. Even though direct ground rupture from faulting directly underneath the subject property is unlikely, the property will be subjected to considerable ground acceleration and shaking from an earthquake event along the nearby faults. The intensity of ground shaking is dependent on distance from faults, earthquake magnitude and duration, and seismic characteristics of foundation soils and bedrock. Soil Liquefaction It is our opinion that due to the relatively high density of the competent natural and compacted fill soils (after remedial grading recommended herein) prevalent at the site; the lack of near-surface groundwater and the grain size characteristics of the in-situ soils, the risk for seismically induced soil liquefaction is very low. FINDINGS, CONCLUSIONS AND RECOMMENDATIONS In general, we concur and agree with the fmdings, conclusions and recommen- dations presented in the above-mentioned Report and Update, and said findings, conclusions and recommendations are still valid and applicable for the proposed site development. S I, Project No. 13-1 147H1 Ace Civil Engineering 06/05/14 Page 6 Gibraltar Street The following addendum recommendations are made, however, as supplement to the recommendations presented in the subject Report and Update. If there are discrepancies, the addendum recommendations herein will prevail. Expansiveness of On-site Near Surface Soils I. ome of the near-surface soils encountered on the site possess high expansion potential (Expansion Index = 98). Earthwork 2. The current grading plans for the project were reviewed. The three building pads will remain in their current elevations. Prior to commencement of grading, it is recommended that the site be cleared and grubbed, and all debris and vegetation disposed of offsite. 3, It is recommended that xistingjjflsthJsjng the front of Lot Nos. 400 and 401 be removed. Maximum depths of fill on these lots are on the order of 3 to 7 feet. The bottom of the over-excavation should'be inspected by our firm, and scarified .1 to a depth of 12 inches. The removed soils should then be properly moistened, and uniformly recompacted to at least 90 percent of maximum &density in accordance with A.S.T.M. D1557, until finished grade is achieved.. 4. For Lot No. 401, it is recommended that the upper soils below finished grade .be scarified to a depth of 12 inches, properly moistened and uniformly to at least 90 percent of maximum dry density in accordance with ASTM D1557. All footin S Project No. 13-1147H1 Ace Civil Engineering 06/05/14 Page 7 Gibraltar Street to be extended into the underlying competent formation soils or bedrock. Since the maximum depth of fill soils on Lot No. 400 is only 3 feet, and extends over a relatively small area, it is recommended that the footingf the proposed structure be extended through the compacted fill soils at least 12 the underlying competent formational soils. The upper, surface and near-surface soils on the building pads had been subjected to weathering for decades. It is recommended that the natural soils on Lot Nos. 399 and 400 be scarified to a depth of 12 inches, properly moistened and uniformly compacted to at least 90 percent of maximum dry density, in order to provide adequate support to the concrete slab of the proposed structures. Repair of Surficial Slope Failure It is recommended that the soils loosened by the erosion and sloughing of the existing slope be removed. The building pads along the toe of the existing slope will be widened, excavating and removing the loosened soils. A retaining wall will also be constructed along the bottom of the existing slope. As thee repair work jresses up the existing slope, benches will have to be arovided. The interval and width of the benches required will be determined by field personnel during the remedial grading. The surface of the slopeshoüldbe properly compacted with a sheepsfoot roller. S Project No. 13-1147111 Ace Civil Engineering 06/05/14 Page 8 Gibraltar Street In order to further minimize the potential for future surficial slumping, it is recommended that the slope be planted with deep rooted ground cover and shrubs at 10 feet on center. Foundation and Slab It is recommended that a safe allowable soil bearing value of I1Q r used in the design and checking of continuous or spread footings that are a minimum of 15 and 24 inches in minimum horizontal dimension, respectively, and are embedded at least 24 inches into the competent natural or compacted filled ground. The above safe allowable soil bearing va1ueiiiaybe further increased by one third when con sideripg.~~nd and/or seismic forces. The concrete slab for the proposed structures should be at least 4 '/2 inches net in thickness, and be reinforced with a minimum of #3 rebars at 18 inches on center in both directions, placed at mid-height of concrete slab. The concrete slab should be underlain by 4 inches of clean sand and a vapor barrier in moisture sensitive areas. The continuous footings should be reinforced with a minimum of 4 #5 rebars; two rebars located near the top, and the other two rebars near the bottom of the footings. Isolated pier footings should be reinforced with 2 #5 rebars in both Project No. 13-1 147H1 Ace Civil Engineering 06/05/14 Page 9 Gibraltar Street directions, placed near the bottom of the footings. Please note that the above slab and foundation reinforcements are based on soil characteristics only. and should be superceded by the requirements of the project architect or structural engineer. It is recommended that the moisture content of the subgrade soils beneath the proposed structures be maintained at approximately 120% of optimum moisture content. However, no flooding of the foundation soils is permitted immediately prior to the placement of concrete. It is recommended that the foundation for the proposed structure be setback at least 7 feet back from the top of the fill slope. Foundations placed closer to the top of the slope than 7 feet should be deepened such that the outer edge of the footing along the bottom is at least 7 feet back from the face of slope at that level. For footings subject to lateral forces, such as those of a retaining wall, the above setback should be increased to 10 feet. It is further fecbmmended that the foundation trench excavations beiñèëtedby' - iir firm prior to the placement of concrete. Any loose and/or unsuitable soils encothitered should be removed and/or replaced under our direction. Retaining Wall Design It is recommended that retaining walls be designed to withstand the pressure exerted by equivalent fluid weights given on the following page: LI Project No. 13-1147H1 Ace Civil Engineering Gibraltar Street 06/05/14 Page 10 Backfill Surface (horizontal : vertical) Level 2:1 1¼:1 Equivalent Fluid Pressure (pcf) 35 50, 58 The above values assume that the retaining walls are unrestrained from movement, and have a granular backfill. For retaining walls restrained from movement at the top, such as basement retaining walls, an uniform horizontal pressure of 7H (where H is the height of the retaining wall in feet) should be applied in addition to the active pressures recommended above. All retaining walls should be supplied with a backfill drainage system adequate to prevent the buildup of hydrostatic pressure. The subdrain should consist of one- inch gravel and a perforated pipe near the bottom of the retaining wall. The width of this subdrain should be at least 12 inches, and extend at least 2/3 height of the retaining wall. The subdrain should be enclosed in a geotextile fabric such as Mirafi 140N or equal. Seismic Earth Pressure Seismic earth pressures can be taken as an inverted triangular distribution with a maximum pressure at the top equal to 1 5H pounds per square foot (with H being the height of the retained earth in feet. Thipressure is in addition to the static , design wall load. The allowable passive pressure and bearing capacity can be Project No. 13-1147111 Ace Civil Engineering 06/05/14 Page 11 Gibraltar Street increased by 1/3 in determining the stability of the wall. A factor-of-safety of 1.2 can be used in determining the stability of the retaining wall under seismic conditions. Lateral Loading To resist lateral loads, it is recommended that the pressure exerted by an equivalent fluid weight of 350 pcf be used for footings or shear keys poured neat against competent natural or compacted fill soils. The upper 12 inches of material in areas not protected by floor slabs or pavements should not be included in the design for passive resistance. This value assumes that the horizontal distance of the soil mass extends at least 10 feet or three times the height of the surface generating the passive pressure, whichever is greater. A coefficient of sliding friction of 0.35 may be used for cast-in-place concrete on competent natural or compacted fill soils. Footings can be designed to resist lateral loads by using a combination of sliding friction and passive resistance. The coefficient of friction should be applied to dead load forces only. All backfill soils behind the retaining wall should Consist of soils having low expansion potential (Expansion Index < 50), and be compacted at least 90 percent of maximum dry density Seismic Coefficients The seismic design factors were determined in accordance with the 2010 S Project No. 13-1147W Ace Civil Engineering Gibraltar Street 06/05/14 Page 12 California Building Code, and presented below: Site Coordinates: Latitude 33.0860 Longitude = 117.2475 Site Class: = D Site Coefficient Fa = 1.040 Site Coefficient Fv = 1.565 Spectral Response Acceleration At Short Periods Ss = 1.153 Spectral Response Acceleration At 1-second Period SI 0.435 Sms = FaSs = 1.200 Smi = FvS1 0.681 Sds = 2/3*Sms = 0.800 Sd1 = 2/3*Sm1 = 0.454 Preliminary Structural Pavement Section Design 23. For preliminary design purposes, it is recommended that a structural pavement section of 3 inches of asphaltic concrete over 6 inches of Class 11 base material over compacted subgrade be used. 24 The upper 8 inches of subgrade and base material should be compacted to at least 95 percent of maximum dry density. 25. For PtC pavement sections, it is recommended that the pavement section be 5 '/ inches in thickness, and be reinforced with #3 rebars at 18 inches on center in - both directions, placed at mid-height of concrete slab. Control joints at 12-foot intervals should also be provided. Fl S Project No. 13-1 147H1 Ace Civil Engineering 06/05/14 Page 13 Gibraltar Street Utility Trench Backfill It is recommended that any backfill soils placed in utility trenches located within 5 feet of any improvements and deeper than 12 inches, or backfill placed in any trench located 5 feet out or more from a building and deeper than 5 feet, be compacted to at least 90 percent of maximum dry density. Surface Drainage and Lot Maintenance Adequate drainage control and proper maintenance of all drainage facilities are imperative to minimize infiltration of surface water into the underlying soil mass in order to reduce settlement potential and to minimize erosion. The building pad should have drainage swales which direct storm and excess irrigation water away from the structure and into the street gutters or other drainage facilities. No surface runoff should be allowed to pond adjacent to the foundation of structures. Concrete Flatwork It is recommended that concrete flatwork be 3 1/2 inches in thickness and reinforced with 6 x6-10/1O welded wire fabric placed at mid-height of slab. One- inch expansion joints should be provided at 15-foot intervals; with ¼ inch weakened plane contraction joints at 5-foot intervals. LIMITATIONS The opinions and recommendations presented in this report are based upon surficial observations and logical projections inferred from observed conditions and the assumption that the soil conditions do not deviate appreciably from those encountered. Should conditions v-arv-~omL-tbast-~~,t-eA—h-ere-in be -developmental construction phase, this firm should be notified immediatejoth.a,,,, qualified soil engineer can inspect the site conditions and evaluate the potential effects S Project No. 13-1 147H1 Ace Civil Engineering Gibraltar Street 06/05/14 Page 14 This report has been prepared in accordance with generally accepted standards of geotechnical engineering practice at the time of its preparation. No other warranties, expressed or implied, are made as to the professional consultation and recommendations contained herein. This report is provided for the exclusive use of the client or his /7 1 Respectfully sub ed, ALLIED E TECHNO)GY ROBERT C , P.E. NoC-24 13 / ExP1z131_ / /i t4o.G00198-. - Etp 12I31. / lAll,"IM-fiftwol) JUN 16 2014 LA - L.LIJt1V1ENT ENGINEERING TABLE OF CONTENTS PAGE NO. INTRODUCTION . I PROPOSED DEVELOPMENT .......................................I Ill. CONCLUSIONS ..................................................I IV. RECOIVIIVIEF.JDATJOF.IS .............................................2 Remedial Grading and Earthworks .................................2 Foundations and Slab-on-Grade Floors .............................8 Exterior Concrete /Flatwork .....................................10 Soil Design Parameters ........................................11 Asphalt and PCC Pavement Design ..............................12 General Recommendations ................................ 13 VIII. LIMITATIONS ...................................................16 PLATE NO. RegionalIndex Map .......................... ................. ........ I SitePlan ...........................................................2 Retaining Wall Drain Detail .............................................3 Isolation Joints and Re-entrant Corner Reinforcement .....................4 Preliminary Soil and Geotechnical Investigation Report APPENDIX A Graded Hillside Project, Gibraltar Street, near Jerez Court La Costa, Carlsbad, San Diego County. PROPOSED MULTI-UNIT ATTACHED RESIDENTIAL DWELLINGS GIBRALTER STREET, JEREZ COURT LA COSTA, CALIFORNIA INTRODUCTION The purpose of this report is to update our "Preliminary Soil and Geotechnical Investigation, Graded Hillside Project, Gibraltar Street, Jerez Court, La Costa, San Diego County, California," dated February 20, 1991. Our efforts in this regard included a detailed review of the referenced report and most recent plans in addition to a site visit conducted by our, Engineering Geologist. The study property location is shown on a Regional Index Map enclosed with this report as Plate 1. The referenced report has been reviewed in connection with this work and a copy of the report is included as Appendix A. PROPOSED DEVELOPMENT The scope of the planned new development is comparable to the proposed development addressed in the referenced Geotechnical Investigation. Current plans submitted to us depict multi-unit attached residential dwellings, extensive retaining walls, and associated improvements. A copy of the most current Site Plan is enclosed herein as Plate 2. CONCLUSIONS The site remains substantially unchanged from the original geotechnical investigation and subsequent referenced report. Based on our review of drawings made available to us, and from a geotechnical engineering point of view, the proposed development is in substantial compliance with the referenced report. The conclusions and recommendations put forth in that report remain valid and should be implemented during the construction phase except where superceded in the following sections. The following comments are also appropriate and should be considered and/or incorporated into the final plans where appropriate and applicable: * All g ~Qeotechnical Investigation rading should be conducted per the referenced Geotechnical Invest report should be considered as a part of the \'INJE & MIDDLETON ENGINEERING, INC. 0 2450 Vineyard Avenue • Escondido, California 92029-1229 0 Phone (760) 743-1214 j PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 2 GIBRALTER STREET. JEREZ COURT, LA COSTA JULY 1. 2004 * All grading operations including removals, suitability of earth deposits used as compacted fill, and compaction procedures should be continuouslyins pected and tested by the project geotechnicäl consultant and presented iii the final as-graded compaction report. The nature of finished subgrade soils should also be confirmed in the final compaction report at the completion of grading. * Final foundation plans may also be reviewed by the project geotechnical consultant for conformance with the requirements of the referenced geotechnical investigation report, More specific, recommendations may be necessary and should be given when final grading and architectural/structural drawings are available. IV. RECOMMENDATIONS The following recommendations are consistent with the indicated geotechnical conditions at the project site and should be reflected on the final plans and implemented during the construction phase. All following recommendations, where applicable, supercede those put forth in the previous report. Added or modified recommendations may also be appropriate and can be provided at the plan review phase when final plans are available: A. Remedial Grading and Earthworks Cut-fill and remedial grading techniques should be used in order to achieve final design grades and improve soil conditions beneath the new structures and improvements. All ground preparations and project, construction should be completed in accordance with the Appendix Chapter 33 of the Uniform Building Code, City of Carlsbad Grading Ordinances, the Standard Specificatipns for Public Works Construction, and the requirements of the following sections: 1. Clearing and Grubbing: Existing vegetation, deleterious materials 'and debris should be removed from areas to receive new 'fills, structures, and improvements plus 10 feet where possible, or as directed in the field. The prepared ground should be inspected and approved by the project geotechnical engineer, or his designated field representative prior to remedial grading work. Abandoned pipes and utility lines should be properly removed, and replaced, or plugged as approved in the field. Voids created by removals of the abandoned underground pipes and structures should be properly backfilled in accordance with the requirements of this report. \'INJE & MIE)DLETON ENGINEERING, INC. • 2450 Vineyard Avenue Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 3 GIBRALTER STREET, JEREZ COURT, LA COSTA JULY 7, 2004 Non-uniform Bearing Soil Transitioning: Non-uniform ground transition from excavated cut to placed fill should not be permitted underneath the proposed structures and improvements. Building foundations1 floor slabs, improvements, and retaining wall foundations should be supported entirely on compacted fills or founded entirely on competent undisturbed cut ground. Transition pads will require special treatment. The cut portion of the cut-fill pads plus 10 feet should be undercut to a sufficient depth to provide for a minimum of 3 feet of compacted fill mat below rough finish grades or at least 12 inches of compacted fill beneath the deepest footing whichever is more. In the roadways, driveway, parking and on-grade slabs/improvement transition areas there should be a minimum of 12 inches of compacted soils below rough finish subgrade. Fill Materials and Compaction: Soils generated from on-site removals and over-excavations will predominantly consist of poor to marginal quality plastic, moisture sensitive clay-rich deposits. Plastic clayey soils typically require additional processing, mixing and moisture conditioning efforts in order to manufacture a uniforrt homogeneous mixture suitable for reuse as new compacted fills. fill soils should be clean deposits free of roots, stumps, vegetation, deleterious matter, thidUñUItbIe pro geotechnical consultant. Uniform bearing soil conditions should be constructed at the site by the remedial grading and earthwork operations. Site soils should be adequately processed, thoroughly mixed, moisture conditioned to 3% to 5% above the optimum moisture levels or as directed in the field, placed in thin uniform horizontal lifts and mechanically compacted to a minimum of 90% of the corresponding laboratory maximum dry density per ASTM D-1557, unless otherwise specified. Fill soils placed within areas subject to potential flood inundation should be mechanically compacted to a minimum of 90% of the laboratory maximum dry . density (ASTM D-1557). Slope protection and erosion control facilities should be installed as shown on the approved CMI drawings. 4. Capping and Select Grading: Final bearing and subgrade soil mixture at the . completion of remedial grading is anticipated to consist of moisture sensitive potentially expansive deposits with detrimental affects which will require .g,hnical and structural mitigation designs as provided in the following sections. Select grading and capping of the site may also be considered which - will allow more conventional foundations/slab and paving designs. In this case, \1INJJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 4 GIBRALTER STREET, JEREZ COURT, LA COSTA JULY 7, 2004 the upper 3 feet in the building envelope plus 10 feet, and upper 1Y2 feet in the paving and improvement areas plus 3 feet should be capped with non- expansive to very low expansive sandy granular import soils (expansion index less than 21) compacted as specified herein. 1 Import sandy soils should also be considered for the project wall backfills. project geotechnical consultant prior to the delivery to the site. In the event only the building envelope plus 10 feet is capped with non- expansive to very low expansive sandy import soils within the upper 3 feet, a subsurface drainage system consisting of a minimum .2 feet deep by 2 feet wide trench with 4 inches diameter perforated pipe (SDR 35) surrounded with %-inch crushed rocks and wrapped in filter fabric (Mirafi 140 N) installed below the capping soils, will be required as directed in the field. 5. Permanent Graded Slopes: Project graded slopes should be programmed for 2:1 gradients maximum. Graded fill slopes constructed at 2:1 gradients will be grossly stable with respect to deep seated and surficial failures for the anticipated design maximum vertical heights. Graded cut slopes should be reconstructed as stabilization fill slopes to develop stable embankments, or retaining walls may be constructed at the toe of the graded cut slope for additional support. All fill slopes shall be provided with a lower keyway. The keyway for the building pad fill slopes should maintain a minimum depth of 10 feet into the competent bedrock units with a minimum width of 20 feet as approved by the project geotechnical engineer or his designated representative The keyway should expose competent bedrock units throughout with the bottom heeled back a minimum of 2% into the natural hillside, and inspected and approved by the project geotechnical' engineer. Additional level benches should be constructed into the-natural hillside as the fill slope cojjstruction progresses. Initial keyway development into the competent and stable formational units should be inspected and approved by the project engineering geologist prior to any fill placement. Locally deeper keyway depths should be anticipated. The keyway for the driveway fill slopes should maintain a minimum depth of 3 . 1 feet into the firm native ground with a minimum width of 12 feet as approved by the project geotechnical engineer or his designated representative. Bottom of , keyway stabilization by placing Geogrid earth reinforcement may also be 1 necessary and should be anticipated. . . I . . 0 V!NJE & M!DDLITON ENGINEERING, INC. ' 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 7434214 I PRELIMINARY GEOTECHNICAL UPDATE REPORT GIBRALTER STREET, JEREZ COURT, LA COSTA PAGE 5 JULY 7. 2004 Fill slopes should also be compacted to 90% (minimum) of the laboratory standard out to the slope face. Over-building and cutting back to the compacted core, or backrolling at a minimum of 3 feet vertical increments and "track-walking" at the completion of grading is recommended for site fill slope construction. Geotechnical engineering inspections and testing will be necessary to confirm adequate compaction levels within the fill slope face Temporary Construction Slopes: Unsupported temporary construction slopes necessary during the removals, over-excavations and wall constructions within the project existing fills, topsoil, terrace deposits, highly weathered and friable formational units should be laid back at 1:1 or flatter gradients as directed in the field. Elsewhere, temporary slopes less than 10 feet high maximum developed within the on-site competent formational units may be constructed at near vertical within the LozecL feet and laid back at 1/z:1 gradients within the upper portions. Trenching within the site upper soils or weathered friable formational units may be laid back at 2:1 gradients or provided with temporary shoring support. The new fill wall backfill should be tightly keyed-in and benched into the temporary slopes as the filling/backfilling progresses. Temporary shoring support will also be required for all vertical trenches greater than 3 feet unless otherwise approved by the project geotechnical consultant. Any continuous shoring technique which can allow safe and stable excavations may be-considered provided it is approved by the owner or his designated project consultants. Minor sloughing of the temporary slope face may occur requiring maintenance or cleanup. All temporary construction slopes require continuous geotechnical j inspections during the grading and wall construction operations. Additional recommendations including revised slope gradients, setbacks and the need for additional shoring support should be, given at that time as necessary. The project contractor shall also obtain appropriate permits, as needed, and conform to Cal-Osha and local governing agencies requirements for trenching/open excavations and safety of the workmen during construction. Wall Back Drainage System: All site retaining walls should be provided with an adequate back drainage system. The wall back drain system should consist of a minimum 18 inches wide trench excavated to the depths of the wall foundation level. A minimum 4-inch diameter, Schedule 40 (SDR 35) perforated pipe surrounded with a minimum of 2.25 cubic feet per foot of %- crushed rocks wrapped in filter fabric (Mirafi 140 N), or Caltrans Class 2 permeable- aggregate should be used. The perforated drain pipe should be VINJE & MIDDLETON ENGINEERING, INC. 0 2450 Vineyard Avenue 0 Escondido. California 92029-1229 1 Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 6 GIBRALTER STREET, JEREZ COURT. LA COSTA JULY 7. 2004 installed at suitable elevations to allow for adequate fall via a non-perforated solid pipe to an approved outlet. Filter fabric can be eliminated if Class 2 permeable material is used. A typical wall back drain system is depicted on the enclosed Plate 3. Appropriate waterproofing should be provided behind the -- walls. Protect pipe outlet as necessary. B. Surface Drainage and Erosion Control: A critical element to the continued 1 stability of the graded building pads is an adequate surface and storm water drainage control, and the installation of drainage control facilities. This can most effectively be achieved by appropriate vegetation cover and the 1 installation of the following systems: * Periods of prolonged rains can result in flowing surface water within the i swale area of the study site. Storm water and erosion control facilities j should be installed per approved plans. * Drainage swales should be provided at the top and toe of the graded slopes per project civil engineer design. 1 * Building pad surface run-off should be collected and directed away from the planned buildings and improvements to a selected location in a controlled manner. Area drains should be installed. * The finished slope should be planted soon after completion of grading. Unprotected slope faces will be subject to severe erosion and should not be allowed. Over-watering of the slope faces should also not be allowed. Only the amount of water to sustain vegetation should be provided. * Temporary erosion control facilities and silt fences should be installed during the construction phase periods and until landscaping .is fully established as indicated and specified on the approved project grading/erosion plans. 9. Engineering Inspections: All grading operations including removals, suitability of earth deposits used as compacted fills, and compaction procedures should be continuously inspected and tested by the project geotechnical consultant and presented in the final as-graded compaction report. The nature of finished subgrade soils should also be confirmed in the final compaction report at the completion of remedial grading. Geotechnical engineering inspections shall include but not limited to the following: .1 VINJE & MIDDLETON ENGINEERING, -INC. 2450Vineyard Avenue 0 Escondido, California 92029-1229 0 Phone (760) 743-1214 1 PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 7 GIBRALTER STREET, JEREZ COURT, LA COSTA JULY 7, 2004 * Initial Inspection - After the grading/brushing limits have been staked but before grading/brushing starts. .1 * Bottom of over-excavation inspection - After the natural ground or competent formational rock is exposed and prepared to receive fill but before fill is ] placed. - * Excavation inspection - After the excavation is started but before the vertical depth of excavation is more than 5 feet. Local and Cal-Osha safety requirements for open excavations apply. * Fill/backfill inspection - After the fill/backfill placement is started but before the vertical height of fill/backfill exceeds 2 feet. A minimum of one test shall be required for each 100 lineal feet maximum with the exception of wall backfills where a minimum of one test shall be required for each 25 lineal feet maximum. Wall backfills shall also be mechanically compacted to at least 90% compaction levels unless otherwise specified. Finish rough and final pad grade tests shall be required regardless of fill thickness. * Foundation trench inspection - After the foundation trench excavations but before steel placement. * Foundation bearing/slab subgrade soils inspection - Prior to the placement of concrete for proper moisture and specified compaction levels. * Foundation/slab steel inspection - After steel placement is completed but before the scheduled concrete pour. * Subdrain/wall back drain inspection - After the trench excavations but during the actual placement. All material shall conform to the project material specifications and approved by the project soils engineer. * Underground utility/plumbing trench inspection - After the trench excavation, but before placement of bedding or installation of the underground facilities. Local and Cal-Osha safety requirements for open excavations apply. Inspection of pipe bedding may also be required by the project geotechnical engineer. * Underground utility/plumbing trench backfill inspection - After the backfill placement is started above the pipe zone but before the vertical height of backfill exceeds 2 feet. Testing of the backfill within the pipe zone may also be required by the governing agencies. Pipe bedding and backfill materials VINJE &. MDDLETON ENGINEERING, INC. 0 2450 Vineyard Avenue • Escondido, California 92029-1229 0 Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 8 GIBRALTER STREET, JEREZ COURT, LA COSTA JULY 7, 2004 shall conform to the governing agencies requirements and project soils report if applicable. All trench backfills shall be mechanically compacted to a minimum of 90% compaction levels unless otherwise specified. Plumbing trenches over 12 inches deep maximum under the interior floor slabs should also be mechanically compacted and tested for a minimum of 90% compaction levels. * Pavement/improvements subgrade and basegrade inspections - Prior to the placement of concrete or asphalt for proper moisture and specified compaction levels. B. Foundations and Slab-on-Grade Floors The following recommendations and geotechnical mitigation are consistent with clay to sandy silty clay (CH/CL), medium to high expansion potential (expansion index less than 131) foundation bearing soil anticipated at finish grade levels. Added or modified recommendations may also be necessary and should be given at the time of the foundation plan review phase. All foundations and floor slab recommendations should be further confirmed and/or revised as necessary at the completion of rough grading based on the actual expansion characteristics of the foundation bearing and subgrade soils. In the event capping of the building pad with non-expansive to very expansive import soils are considered, this office should be notified to provide appropriate revised foundations/slab recommendations: 1. Continuous interior and exterior foundations should be sized at least 15 inches wide and 24 inches deep for single-story and two-story structures. Exterior -i spread pad footings, if any, should be at least 30 inches square and 18 inches deep and structurally tied to the perimeter strip footings with tie beams at least I in one direction. Tie beams should be at least 12 inches wide by 12 inches J deep. Footing depths are measured from the lowest adjacent ground surface, not including the sand/gravel beneath floor stabs. Exterior continuous footings should enclose the entire building perimeter. Flagpole footings also need to be tied together if the footing depth is less than 4 feet below the rough finish grades. 2. Continuous interior and exterior foundations should be reinforced with a minimum of four-#5 reinforcing bars. Place 245 bars 3 inches above the bottom of the footing and 245 bars 3 inches below the top of the fo9ting. Tie beams should also be reinforced with 244 bars top and bottom and #3 ties at \1INJE & MIDDLETON ENGINEERING, INC • 2450 Vineyard Avenue • Escondido California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 9 GIBRALTER STREET, JEREZ COURT, LA COSTA JULY 7, 2004 24 inches on center maximum. Reinforcement details for spread pad footings should be provided by the project architect/structural engineer. The slab subgrade and foundation bearing soils should not be allowed to dry prior to pouring the concrete or additional ground preparations, moisture re- conditioning, and pre-saturation will be necessary as directed in the field. The required moisture content of the bearing soils is approximately 3% to 5610 over the optimum moisture content to the depth of 24 inches below slab subgrade. Attempts should be made to maintain as-graded moisture contents in order to preclude the -needfor pre-saturation of the subgrade and bearing soils. In the case of pre-saturation of the slab subgrade and/or non-monolithic pour (two-pour) system, dowel the slab to the footings using #4 reinforcing bars spaced 18 inches on center and extending at least 20 inches into the footing '1 and 20 inches into slab. The dowels should be placed mid-height in the slab. j Alternate the dowels each way for all interior footings. After the footings are dug and cleaned, place the reinforcing steel and dowels, and pour the footings. This office should be notified to inspect the foundation trenches and reinforcing prior to pouring the concrete. Once the concrete for the footings has cured and underground utilities tested, place 4 inches of :'/B-inch rock over the slab subgrade. Flood with water to the top of the 3/s-inch rock, and allow the slab subgrade to soak until moisture testing indicates that the required moisture content is present. After the slab subgrade soils have soaked, notify this office and schedule for appropriate moisture testing. When the required moisture content has been achieved, place a 10-mil plastic moisture barrier over the 3/8-inch rock, and place 2 inches of clean sand (SE 30 or greater) on top of the plastic. If sufficient moisture is present, flooding/pre-saturation will not be required. The dowels may be deleted, and slab underlayment may consist of 2 inches of clean sand over a 6 mu-plastic moisture barrier over 2 inches of clean sand, and the footings and slab may be poured monolithically. VINJE & MIDDLErON ENGINEERING, INC. ' 2450 Vineyard Avenue s Escondido, California92029-1229 • Phone (760) 743-1214 J PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 10 GIBRALTER STREET, JEREZ COURT, LA COSTA JULY 7, 2004 This office should be notified to inspect the sand, slab thickness, and reinforcing prior to the concrete pour. All interior slabs should be a minimum of 5 inches in thickness reinforced with #4 reinforcing bars spaced 18 inches on center each way, placed 11/2 inôhes below the top of the slab. Interior slabs should be provided with "softcut' contraction/control joints consisting of sawcuts spaced 10 feet on center maximum each. way. Cut as soon as the slab will support the weight of -the saw, and operate without disturbing the final finish which is normally within 2 hours after final finish at each control joint location or 150 psi to 800 psi. The softcuts should be a minimum of %-inch in depth but should not exceed 1-inch deep maximum. Anti-ravel skid plates should be used and replaced with each blade to avoid spalling and raveling. Avoid wheeled equipment across cuts for at least 24 hours. Provide re-entrant corner reinforcement for all interior slabs. Re-entrant corners will depend on slab geometry and/or interior column locations. Plate 4 may be used as a general guideline. Foundation trenches and slab subgrade soils should be inspected and tested for proper moisture and specified compaction levels and approved by the project geotechnical consultant prior to the placement of concrete. C. Exterior Concrete /_Flatwork All exterior slabs (walkways, patios) should be a minimum of 4 inches in thickness, reinforced with. #3 bars at 18 inches on centers in both directions placed 1½ inches below the top of slab. Use 6 inches of 90% compacted clean sand beneath all exterior slabs. Provide "tool joint" or "softcut" contraction/control joints spaced 10 feet on center (not to exceed 12 feet maximum) each way. Tool or cut as soon as the slab will support weight and can be operated without disturbing the final finish which is normally within 2 hours after final finish at each control joint location or 150 psi to 800 psi. Tool or softcuts should be a minimum of %-inch but should not exceed 1-inch deep maximum. In case of softcut joints, anti-ravel skid plates should be used and replaced with each blade to avoid spalling and raveling. Avoid wheeled equipments across cuts for at least 24 hours. VINJE & MIDDLETON ENGINEERING, INC. 0 2450 Vineyard Avenue • Escondido, California 920294229 1 Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 11 GIBRALTER STREET, JEREZ COURT, LA COSTA JULY 7, 2004 3. It is recommended to provide a minimum of 8 inches wide by 12 inches deep thickened edge reinforced with a minimum of 144 continuous bar near the bottom along the free-ends of all exterior slabs and flatworks supported on moisture sensitive expansive soils. All exterior slab designs should be confirmed in the final as-graded compaction report. 0 Subgrade soils should be tested for proper moisture and specified compaction levels and approved by the project geotechnical consultanf prior to the placement of concrete. D. Soil Design Parameters LI The following soil design parameters are based on tested representative samples of on-site selected sandy materials. Potentially expansive plastic clayey soils should not be used for wall backfill soils. All parameters should be re-evaluated when the characteristics of the final soils have been specifically determined: * Design wet density of soil = 119.0 pcf. * Design angle of internal friction of soil = 34 degrees. * Design active soil pressurefor retaining structures = 34 pcf (EFP), level backfill, cantilever, unrestrained walls. * Design at-rest soil pressure for retaining structures = 53 pcf (EFP), non- yielding, restrained walls. * Desigh passive soil pressure for retaining structures = 421 pcf (EFP), level surface at the toe, * Design coefficient of friction for concrete on soil = 0.35. j * Net allowable foundation pressure for certified compacted fill = 1500 psf (minimum 15-inch wide by 24-inch deep footings). * Allowable lateral bearing pressure (all structures except retaining wails) for certified compacted fills = 100 psf/ft. Notes: * Good quality sandy import soils may be considered for site wall backfill purposes which will improve the above specified design parameters. Import J soils for wall backfill will require additional laboratory testing. * Use a minimum safety factor of 1.5 for wall over-turning and sliding stability. However, because large movements must take place before maximum passive resistance can be developed, a minimum safety factor of 2 may be considered VINE & MJDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 0Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 12 GIBRALTER STREET, JEREZ COURT, LA COSTA JULY 7, 2004 for sliding stability particularly where sensitive structures and improvements are 1 planned near or on top of retaining -walls. - * When combining passive pressure and frictional resistance the passive -- component should be reduced by one-third. S * The net allowable bearing pressure provided herein was determined for footings having a minimum width of 15 inches and depth of 24 inches. The indicated value may beincreased by 20% for each additional foot of depth and 5% for each additional foot of width to a maximum of 3500 psf. The allowable 1 foundation pressures provided herein also apply to dead plus live loads and may be increased by one-third for wind and seismic loading. * The lateral bearing earth pressure may be increased by the amount of J designated value for. each additional foot of depth to a maximum of 1500 pounds per square foot. E. Asphalt and PCC Pavement Design Specific pavement designs can best be provided at the completion of rough grading based on R-value tests of the actual finish subgrade soils; however, the following structural sections may be considered for cost estimating purposes only I (not for construction): A minimum section of 3 inches asphalt on 6 inches Caltrans Class 2 aggregate base may be considered for on-site asphalt paving surfaces not within the public or private street right-of-way. Base materials should be compacted to a minimum of 95% of the corresponding maximum dry density (ASTM D-1 557). Subgrade soils beneath the asphalt paving surfaces should also be compacted to a minimum of 95% of the corresponding maximum dry density within the upper 12 inches. Residential PCC driveway and parking areas not within the public or private j street right-of-way supported on medium to high expansive subgrade soils, should be. a minimum of 5% inches in thickness, reinforced with #3 reinforcing bars at 18 inches on centers each way placed 2 inches below the top of slab. j Subgrade soils beneath the PCC parking and driveway should be compacted to a minimum of 90% of the corresponding maximum dry density within the upper 6 inches. Use a minimum 560-C-3250 concrete per Standard I Specifications for Public Works Construction (Green Book) standards. \'INJE &MDDLETON ENGINEERING, INC..' 2450 Vineyard Avenue • Escondido, California 92029-1229 1 Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 13 GIBRALTER STREET. JEREZ COURT. LA COSTA JULY 7. 2004 In order to enhance performance of PCC pavements supported on expansive subgrade soils, a minimum 8 inches wide by 12 inches deep thickened edge reinforced with a minimum of 144 continuous bar placed near the bottom should be considered along the outside edges. Provide "tool joint" or "softcut' contraction/control joints spaced 10 feet on center (not to exceed 15-feet maximum) each way. Tool or cut as soon as the slab will support weight and can be operated without disturbing the final finish which is normally within 2 hours after final finish at each control joint location or 150 psi to 800 psi. Tool or softcuts should be a minimum of 1-inch but should not exceed 11/4-inches deep maximim. In case of softcut joints, anti- ravel skid plates should be used and replaced with each blade to avoid spalling and raveling. Avoid wheeled equipments across cuts for at least 24-hours. Subgrade and basegrade soils should, be tested for proper moisture and specified compaction levels and approved by the project geotechrjical consultant just prior to the placement of the base or asphaltlPCC finish surface. Base section and subgrade preparations per structural section design will be required for all surfaces subject to traffic including roadways, travelways, drive lanes, driveway approaches and ribbon (cross) gutters. Driveway approaches within the public right-of-way should have 12 inches subgrade compacted to a minimum of 95% compaction levels and provided with a 95% compacted Class 2 base section per the structural section design. In the case of expansive subgrade soils, provide-6 inches of Class 2 base under curb and gutters and 4 inches of Class 2 base (or 6 inches of Class Ill) under sidewalks. Base layer under curb and gutters should be compacted to a minimum of 95%, while subgrade soils under curb and gutters, and base and subgrade under sidewalks should be compacted to a minimum of 90% compaction levels. F. General Recommendations J 1. The minimum foundation design and steel reinforcement provided herein are to based on soil characteristics and are not intended to be in lieu of reinforcement . necessary for structural considerations. All recommendations should be further j evaluated based on final as-graded geotechnical conditions and confirmed by • the project architect/structural engineer. S VINJE & MIDDLETON ENGINEERING, INc. 1 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHN!CAL UPDATE REPORT PAGE 14 GIBRALTER STREET, JEREZ COURT, LA COSTA JULY 7, 2004 Adequate staking and grading control is a critical factor in properly completing the recommended remedial and site grading operations. Grading control and staking should be provided by the project grading contractor, or surveyor/civil engineer, and is beyond the geotechnical engineering services. Inadequate staking and/or lack of grading control may result in unnecessary additional grading which will increase construction costs. Footings located on or adjacent to the top of slopes should be extended to a sufficient depth to provide a minimum horizontal distance of 10 feet or one-third of the slope height1 whichever is greater (need not exceed 40- feet maximum) between the bottom outside edge of the footing and face Of slope. This requirement applies to all improvements, and structures including fences, posts, pools, spas, etc. Concrete and AC improvements should be provided with a thickened edge to satisfy this requirement. Expansive clayey soils should not be used for backfilling of any retaining structure. All retaining walls should be provided with a 1:1 wedge of granular, compacted backfill measured from the base of the wall footing to the finished surface, All underground utility and plumbing trenches should be mechanically compacted to a minimum of 90% of the maximum dry density of the soil unless otherwise specified. Care should be taken not to crush the utilities or pipes during the compaction of the soil. Non-expansive, granular backfill soils should be used. On-site soils are potentially expansive moisture sensitive clayey deposits which will undergo continued swelling and shrinkage upon wetting and drying. Maintaining a uniform as-graded soil moisture during the post construction periods is essential in the future performance of site structures and improvements. In no case should water be allowed to pond or accumulate adjacent to the improvements and structures*. Site drainage over the finished pad surfaces should flow away from structures onto the street in a positive manner. Care should be taken during the construction, improvements, and fine grading phases not to disrupt the designed drainage patterns. Roof lines of the buildings should be provided with roof gutters. Roof water should be collected and directed away from the buildings and structures to a suitable location. Consideration should be given to adequately damp-proof/waterproof the basement walls/foundations and provide the planter areas adjacent to the foundations with an impermeable liner and a subdrainage system. \'IN;E & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 0 Phone (760) 743-1214 I PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 15 GIBRALTER STREET, JEREZ COURT, LA COSTA JULY 7, 2004 Based upon the result of the tested soil sample, the amount of water soluble sulfate (SO4) was found to be 0.021 percent by weight which is considered negligible according to the California Building Code Table No. 19-A-4. Portland cement Type I or If may be used. Final plans should reflect preliminary recommendations given in this report. Final foundations and grading plans should also be reviewed by the project geotechnical consultant for conformance with the requirements of the' geotechnical investigation report outlined herein. More specific recommendations may be necessary and should be given when final grading and architectural/structural drawings are available. All foundation trenches should be inspected to ensure adequate footing embedment and confirm competent bearing soils. Foundation and slab reinforcements should also be inspected and approved by the project geotechnical consultant. The amount of shrinkage and related cracks that occur in the concrete slab-on- grades, flatworks and driveways depend on many factors, the most important of which is the amount of water in the concrete mix. The purpose of the slab reinforcement is to keep normal concrete shrinkage cracks closed tightly. The amount of concrete shrinkage can be minimized by reducing the amount of water in the mix. To keep shrinkage to a minimum the following should be considered: * Use the stiffest mix that can be handled and consolidated satisfactorily. * Use the largest maximum size of aggregate that is practical. For example, concrete made with 3/8-lflch maximum size aggregate usually requires about 40 lbs more (nearly 5-gal.) water per cubic yard than concrete with 1-inch aggregate. * Cure the concrete as long as practical. The amount of slab reinforcement provided for conventional slab-on-grade construction considers that good quality concrete materials, proportioning, craftsmanship, and control tests where appropriate and applicable are provided. A preconstruction meeting between representatives of this office, the property owner or planner, city inspector and the grading contractor/builder is recommended in order to discuss grading/construction details associated with the site development. 1. \'IN;E & MIDDLETON ENGINEERING, INC. 0 2450 Vineyard Avenue • Escondido, California 92029-1229 0 Phone (760) 743-1214 I PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 16 GIBRALTER STREET,JEREZ COURT, LA COSTA JULY 7, 2004 VIII. LIMITATIONS The conclusions and recommendations provided herein have been based on all available data.obtained from site observations, research and review of pertinent geotechnical reports and plans, subsurface exploratory excavations, as well as our experience with the soils and foimational materials located in the general area. The materials encountered On the project site and utilized in laboratory testing are believed representative of the total area; however, earth materials may vary in characteristics between excavations. Of necessity we must assume a certain degree of continuity between exploratory excavations and/or natural exposures. It is necessary, therefore, that all observations, conclusions, and recommendations be verified during the grading -operation. In the event discrepancies are noted, we should be contacted immediately so that an inspection can be made and additional recommendations issued if required. The recommendations made in this report are applicable to the site at the time this report was prepared. It is the responsibility of the owner/developer to ensure that these recommendations are carried out in the field. It is almost impossible to predict with certainty the future performance of a property. The future behavior of the site is also dependent on numerous unpredictable variables, such as earthquakes, rainfall, and on-site drainage patterns. The firm of VINJE & MIDDLETON ENGINEERING, !NC.P shall not be held responsible for changes to the physical conditions of the property such as addition of fill soils, added cut slopes, or changing drainage patterns which occur without our inspection or control. The property owner(s) should be aware of the development of cracks in all concrete surfaces such as floOr slabs and exterior stucco associated with normal concrete shrinkage during the curing process. These features depend chiefly upon the condition of concrete and weather conditions at the time of construction and do not reflect detrimental ground movement. Hairline stucco cracks will often develop at window/door corners, and floor surface cracks up to ½-inch wide in 20 feet may develop as a result of normal concrete shrinkage (according to the American Concrete lnstitute).This report should be considered valid for a period of one year and is subject to review by our firm following that time. If significant modifications are made to your tentative development plan, especially with respect to the height and location of cut and fill slopes, this report must be presented to us for review and possible revision. Vinje & Middleton Engineering, Inc., warrants that this report has been prepared within the limits prescribed by our client with the usual thoroughness and competence of the engineering profession. No other warranty or representation, either expressed or implied, is included or intended. \JNJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue 9 Escondido, California 92029-1229 9 Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 17 GIBRALTER STREET, JEREZ COURT, LA COSTA JULY 7, 2004 Once again, should any questions arise concerning this report, please do not hesitate to contact this office. Reference to our Job #04-287-P will help to expedite our response to your inquiries. We appreciate this opportunity to be of service to you. VINJE & MIDDLETON ENGINEERING, INC. Dennis Middleton CEG • a. CEG98o * CERTIFIED * ENGINEERING f" `"s11-10P CAtV ariat O.4tIf4 74 Exp. 1231.05 Steven J. Melzer RG #6953 DM/SMSS/SJM/jt Distribution: Addressee (5) c:rI/rnyfiIes1updates.04I04-287-P JAY co No. 695 ID),," Exp.5-31 LD \'INJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue 0 Escondido, California 92029-1229 0 Phone (760) 743-1214 Z? 4!I: I \ 7f '\- . -. ---- -• •. 1 - . -. \•_-_•. ( I . - Ord ZU I -Q-013.404-2m PD CIL 7f- L , - 8c&O I 25.000 TN IJDll1u1 1" 0fl0ft 1 200 DuLorme. Topo LISA €'. Data copyright of content owner. _ I IF www.dotorme.com — •' j r 112 RETAINING WALL DRAIN DETAIL Typical - no• scale drainage Granular, non expansive backfill Compacted//" Waterproofing Filter Material. Crushed rock (wrapped in filter fabric) or Class 2 Permeable Material Perforated drain pipe W I (see specifications below) Competent, approved soils Or bedrock CONSTRUCTION SPECIFICATIONS: Provide granular; non-expansive backfill soil In 1:1 gradient wedge behind wall. Compact backfill to minimum 90% of laboratory standard. Provide back drainage for wall to prevent build-up of hydrostatic pressures. Use drainage openings along base of wall or back drain system as outlined below. Backdraln should consist of 4" diameter PVC pipe (Schedule 40 or equivalent) with perforations down. Drain to suitable outlet' at minimum 1%. Provide Y4"- 1W crushed gravel filter wrapped in filter fabric (Mirafi 140N or equivalent). Delete filter fabric wrap If Caltrans Class 2 permeable material is used. Compact Class 2 material to minimum 90% of laboratory standard. (Seal back of wall with waterproofing in accordance with architects specifications. - -. Provide positive drainage to disallow ponding of water above wall. Lined drainage ditch to minimum 2% flow away from wall Is recommended. Use 1% cubic foot per foot with granular backfill soil and 4 cubic foot per foot if expansive backfill soil is used. VINJE & MIDDLETON ENGINEERING, INC PLATE 3 (a) (b) ATION JOINTS RACTION JOIN" ENTRANT NER CRACK RE-ENTRANT CC REINFORCEMEN NO. 4 BARS P1 BELOW TOP OF ISOLATION JOINTS AND RE-ENTRANT CORNER REINFORCEMENT Typical - no scale NOTES: Isolation joints around the columns should be either circular as shown in (a) or diamond shaped as shown In (b). If no isolation joints are used around columns, or if the corners of the isolation joints do not meet the contraction joints, radial cracking as shown in (c)may occur (reference Ad). In order to control cracking at the re-entrant corners (±2700 corners), provide reinforcement as shown in (c). Re-entrant corner reinforcement shown herein is provided as a general guideline only and is subject to verification and changes by the project architect and/or structural engineer based upon slab geometry, location, and other engineering and construction factors. VINJE & MIDDLETON ENGINEERING, INC. PLATE 4 APPENDIX A A '41:20: Scale 1'=20' PLATE :2 MV ENGINEERING, INC. 2450 Vineyard Ave., Suite 102 Escondido, CA 92029-1229 ZW 619/743-1214 Fax: 739-0343 Job #1017-91 February 20, 1991 } Mr. Hossein Zomorrodi zomOrrQdi Engineering 5983 Cirrus Street } San Diego, California 92110 Preliminary Soil and Geotechnical Investigation, Graded Hillside Property, Gibraltar Street Near j Jerez Court, La Costa Area of Carlsbad, San Diego County. California Pursuant to your request, MV Engineering, Inc. has completed the - attached investigation of soils and geotechnical conditions at the subject site. - The following report summarizes the results of our field investigation, laboratory analyses, and conclusions, and provides 1 recommendations for the site development as understood. From a j geotechnical engineering standpoint, it is our opinion that the site is suitable for the proposed development provided the recommendations presented in this report are incorporated into the j design and construction of the project. Thank you for choosing NV Engineering, Inc. If you have any 1 questions concerning this report, please do not hesitate to call J us. Reference to our Job #1017-91 will expedite our response to your inquiries. J We appreciate this opportunity toe of service to you. issio MV ENGINEERING, INC. No. 863 Exp. 12-3193 Ralph M. Vinje 4 GE #863 OF Cr RNV/kmh j TABLE OF CONTENTS Page INTRODUCTION. . . . . . . . . . . . . . 1 SITE DESCRIPTION/BACKGROUND . . . . ... 1 PROPOSED DEVELOPMENT. . . . . . . . . . 1 SITE INVESTIGATION. . . . . . . . . . . 2 GEOTECHNICAL CONDITIONS . . . . . . . . 2 A. Earth Materials . . . . . . . . . . . 2 Fill (at) ....... . . . . . 2 Terrace Deposit (Qt). . . . . . . 2 Bedrock (Td). . . . . . . . . . . 2 B. Laboratory Testing/Results . . . . . 3 Maximum Dry Density and Optimum Moisture Content . . . . . 3 In-Place Dry Density and Moisture Content ....... 3 Expansion Index Test...... 4 Direct Shear Test . . . . 4 C. Geologic Structure .........4 D. Seismicity ............ 4 E. Slope Stability. . . . . * . . . 5 VI. CONCLUSIONS/RECOMMENDATIONS ..... 5 A . Grading. . ... ......... . 6 B. Foundations .............6 C. Interior Slabs . . * ........7 D. Exterior Slabs ....... . 8 E. Retaining Walls ...........8 F. Design . . ...... . ..... 9 G. Drainage/Erosion Control . . * 9 H. Pavement . . . . . ........ 10 I. Utility Trench Backfill. . . . 10 J. Plan Review . ........ .10 K. Geotechnical and Construction Inspections ............ 10 L. Preconstruction Conference . * . 11 VII. LIMITATIONS ..............11 (continued) Table of Contents/Page 2 APPENDIXES APPENDIX "A" - SUBSURFACE INVESTIGATION Plate Geotechnical Map ...... . . . . 1 Geologic Cross Sections ...... 2 Test Pit Logs (including Key). . . . 3-7 Isolation Joints and Re-Entrant Corner Reinforcement . . . . . . . . 8 Typical Wall Drainage Detail . . . . 9 APPENDIX "B" - SPECIFICATIONS FOR CONSTRUCTION OF CONTROLLED FILLS, AND UNIFIED SOIL CLASSIFICATION PRELIMINARY SOIL AND QEOTECHNICAL INVESTIGATION GRADED HILLSIDE PROJECT GIBRALTAR STREET NEAR JEREZ COURT LA COSTA AREA OF CARLSBAD SAN DIEGO COUNTY, CALIFORNIA INTRODUCTION The study property consists of three vacant graded sites along the north side of Gibraltar Street in La Costa. The site location is depicted on the Vicinity Map included on the Geotechnical Map attached with this transmittal as Plate 1. We understand that the property is presently planned to support several attached dwelling units in separate buildings as shown on Plate 1. The purpose of this study was to determine geotechnical conditions in the planned construction areas and their influence on the planned improvements. SITE DESCRIPTION/BACKGROUND The study site is located within graded hillside terrain north of and below La Costa Avenue. Access onto the property is provided by Gibraltar Street which defines the north property boundary. The site consists of three level pad surfaces which are surrounded by graded slopes. Rear areas are terminated by a large cut slope which ascends as much as 70 feet onto off site terrain above. Smaller side and front slopes define each of the three pads as shown on Plate 1. Slope gradients are 1½:l (horizontal to vertical). Surface areas are bare or support a light cover of native grass. Site drainage sheetflows over surface areas toward Gibraltar Street. Some erosion of front slopes has occurred as a result of concentrated run-off. Technical records for the grading are unavailable. Aerial photo- graphs and topographic maps of the area indicate that site grading took place between 1960 and 1977. PROPOSED DEVELOPMENT Detailed development plans for the project are presently unavailable. However, we understand that the site is planned to support attached dwelling units as shown on Plate 1. Construction will be conventional wood-frame and stucco supported by continuous foundations. Slab-on-grade floors are planned for lower units. PRELIMINARY BOIL AND GEOTECHNICAL INVESTIGATION PAGE 2 GIBRALTAR STREET, LA COSTA AREA OF CARLSBAD FEBRUARY 20, 1991 Planned grades (shown on Plate 1) indicate modest cut/fill grading to establish new, level building surfaces. A maximum cut of 12 feet and a maximum fill of seven feet is planned. Retaining walls are proposed throughout as shown. SITE INVESTIGATION GeotechniCal conditions ,at the site were determined chiefly by field mapping of available surface exposures and the excavation of seven exploratory trenches dug with a tractor-mounted bac]thoe. The trenches were logged by our project geologist who retained representative soil/rock samples for laboratory testing. Results of the testing are tabulated in a following section. Geologic cross sections and logs of the test trenches are attached as Plates 2 through 7 (including the Key). GEOTECHNICAL CONDITIONS A. Earth Materials - The following earth materials were encountered at the project and will affect site development: Fill (af) - Fill soils occur at the project, particularly beneath front areas of the graded parcels. The fill consists chiefly of locally derived sands and silts with included rock fragments. The fill generally occurs in a loose condition. Terrace Deposit (Qt) - Natural Terrace Deposit soils underlie the front portion of the project. These are dark colored clay-silt deposits which mantled lower hillside terrain along the southern margin of San Marcos Creek. Deposits at the site occur in a soft to stiff condition. Bedrock (Td) - Formational sedimentary rocks underlie rear areas of the property including the large ascending slope. The rocks consist of interbedded sandstone and siltstone units which are widely exposed in local hillside terrain to the south. On-site exposures occur in a firm to locally hard condition. Details of the earth materials underlying the project are included on the enclosed logs (Plates 4 through 7). The approximate distribution of major earth materials is depicted on Plate 1 and on the Geologic Cross Sections enclosed as Plate 2. PRELIMINARY SOIL AND GEOTECHNICAL INVESTIGATION PAGE 3 GIBRALTAR STREET, LA COSTA AREA OF CARLSBAD FEBRUARY 20, 1991 B. Laboratory Testing/Results - Excavations of on-site earth deposits will result in soils which have been grouped into the following soil types: SOIL TYPES Soil/Rock Type 1 2 3 4 Soil DescriDtiofl light brown clayey sand/ sandy clay light colored silty sand tan to brown silty sand dark brown silty to sandy clay The following tests were conducted in support of this study: Maximum Dry Density and Optimum Moisture Content - The maximum dry density and optimum moisture content of selected soil types were determined in accordance with ASTM D-1557- 78. The results are tabulated below. Optimum Test Soil Maximum Dry Moisture Location Type Density (pcf) Content 1%) TP 1@5 2 115.7 15.3 TP 2@2' 4 114.5 15.6 TP = Test Pit These results may be used during the grading where applicable. In-Place Dry Density and Moisture Content - In-place dry densities and moisture content of representative chunk soil samples were determined using the water displacement method. Results are presented below. j Test Soil Dry Density Field Moisture Location Type (pcf) (%) TP 1@5' 2 133.8 7.2 TP 1@8' 2 101.1 17.3 TP 1@8' 2 108.4 17.0 TP 1@10' 3 129.8 12.0 TP 1@13 3 110.1 17.0 II PRELIMINARY SOIL AND GEOTECHNICAL INVESTIGATION PAGE 4 GIBRALTAR STREET, LA COSTA AREA OF CARLSBAD FEBRUARY 20, 1991 Expansion Index Test - The potential for on-site soils to change in volume in response to moisture fluctuations was determined by expansion index tests. The tests were performed in accordance with the Uniform Building Code Standard Procedure 29-2. Results are presented below. Remolded Saturated Sample Moisture Moisture Expansion Location Content (%) Content (%) Index TP 1@8' 19.3 29.3 46 TP 2@2' 12.8 33.6 98 Direct Shear Test - A direct shear test was performed on a representative site soil sample for strength parameters in the lateral load and bearing capacity calculations. Three soil specimens were prepared by molding them in 2-inch diameter, 1-inch high rings to 90 of the corresponding maximum dry density and optimum moisture content and soaked overnight. The specimens were loaded with normal loads of 1, 2, and 4 KSF respectively and sheared to failure in an undrained shear. The results are presented below. Wet Angle of Apparent Soil Density Int. Frio. Cohesion Location Type (pcf) 0 (degree) c, (psf) TP 1@5' 2 119.0 34 146 Geologic Structure - Bedding conditions within on-site bedrock are poorly developed. However, noted exposures indicate nearly flat-lying conditions throughout. Faults or significant shear zones are not in evidence at the project site. Seismicity - As with most areas of California, the San Diego region lies within a seismically active zone. However, coastal areas of the county are characterized by low levels of seismic activity relative to inland areas to the east. During a 40-year period (1934-1974), 37 earthquakes were recorded in San Diego coastal areas by the California Institute of Technology. None of the recorded events exceeded a Richter magnitude of 3.7 nor did any of the earthquakes generate more than modest ground shaking or significant damages. Most of the recorded events occurred along various offshore faults which characteristically generate modest earthquakes. PRELIMINARY BOIL AND GEOTECHNICAL INVESTIGATION IPAGE 5 GIBRALTAR STREET, LA COSTA AREA OF CARLSBAD FEBRUARY 20, 1991 Historically, the most significant earthquake events which affect local areas originate along well known, distant fault zones to the east. Less significant events have been recorded along off shore faults to the west. The following list represents the most significant active fault which typically impact the region. Fault Zone Elsinore Fault San Jacinto Fault San Andreas Fault Coronado Bank Fault Distant from Site 28 miles 57 miles 82 miles 20 miles More recently, the number of seismic events which affect the region appears to have heightened somewhat. Nearly 40 earthquakes of magnitude 3.5 or higher have been recorded in coastal regions between January, 1984 and August, 1986. Most of the earthquakes are thought to have been generated along offshore faults. For the most part, the recorded events remain moderate shocks which typically resulted in low levels of ground shaking to local areas. A notable exception to this pattern was recorded on July 13, 1986. An earthquake of magnitude 5.3 shook North Coast coastal areas resulting in $400,000 in damages and injuries to 30 people. The quake occurred along an offshore fault located nearly 30 miles southwest of Oceanside. The event resulted in moderate to locally high levels of ground shaking in areas of the study site. The increase in earthquake frequency in the region remains a subject of speculation among geologists. However, the 1986 event is thought to represent the highest levels of ground shaking which can be expected at the study site as a result of seismic activity. Ground separation during expected earthquake events is not antici- pated at the study site. E. Slope Stability - Existing site slopes do not evidence geologic instability. Underlying bedrock units are flat-lying, sedi- mentary rocks which are expected to perform well in modest slopes planned for redevelopment. The stability of off-site slopes is beyond the scope of this transmittal. VI. CONCLUSIONS/RECOMMENDATIONS Based upon the foregoing investigation, development of the study property for residential purposes is feasible from a geotechnical viewpoint. The property is underlain by old fill and Terrace Deposit soils which, in their present condition, have a potential PRELIMINARY SOIL AND GEOTECHNICAL INVESTIGATION PAGE 6 GIBRALTAR STREET, LA COSTA AREA OF CARLSBAD FEBRUARY 20, 1991 for detrimental soil movement. Loose, compressible soils, as well as expansive soils, are present at the site. Consequently, regrading of near-surface soils is recommended in order to create safe and stable building surfaces. Recommendations given below are consistent with site geotechnical conditions and should be incor- porated into finalized plans. A. Grading: Grading operations at the property should generally be conducted in accordance with the enclosed "Specifications for Construction of Controlled Fills" attached with this report as Appendix "B" Prior to grading, site vegetation and other deleterious debris should be removed from the property. Near surface soils should be excavated to grade elevations depicted on Plate 1. The indicated removal depths apply to the existing plans and the finished elevations given on Plate 1. Changes in the plans will likely require modifications in the removal elevations given herein. After completion of the indicated removals, planned grades should be achieved by on-site soils as properly compacted fill. The fill should be brought to optimum moisture levels and mechanically compacted in thin, horizontal lifts to a minimum 90% of the laboratory maximum density value. On-site soils may be re-used in compacted fill. However, dark colored Terrace Deposit soils represent the most expan- sive deposits at the site. Consideration should be given to placing these deposits within the deeper fills as a means of minimizing the expansive potential of finish grade soils. B. Foundations - At the completion of rough grading, this office should confirm by testing the actual expansion potential of finish grade soils so that more specific foundation/slab recommendations can be provided. However, based upon site soil characteristics, it is assumed that expansive soils will be exposed at finish grade. Consequently, the following founda- tion/slab recommendations are provided for preliminary design and estimating purposes. 1. Foundations should be founded a minimum depth of 24° inches below the lowest adjacent grade (not including sand/gravel under the slab). Footings should maintain a minimum width of 12 inches. Isolated square footings are not recommended. PRELIMINARY SOIL AND GEOTECHNICAL INVESTIGATION PAGE 7 GIBRALTAR STREET, LA COSTA AREA OF CARLSBAD FEBRUARY 20, 1991 Foundations should be reinforced with four #4 bars, two placed three inches below the top and two bars placed three inches above the bottom of the footing. Dowel the slab to the footings using #4 reinforcing bars spaced 18 inches on center extending 20 inches into the footing and slab. The dowels should be placed mid-height in the slab. Alternate the dowels each way for all interior footings. After the footings are dug and cleaned, place the reinforcing steel and dowels and pour the footings. This office must be notified to inspect the footings and reinforcing prior to pouring concrete. C. Interior Slabs: All utility trenches under slabs in expansive soils should be backfilled with sand (S.E. 30 or greater) and flooded with water to achieve compaction. Once the concrete for the footings has cured and underground utilities tested, place four inches of pea gravel (?i_inch rock) over the slab subgrade. Flood with water to the top of the pea gravel, and allow the slab subgrade to soak for approximately seven to 10 days. The required moisture content of the slab subgrade soils is 3% to 5% over the optimum moisture content at a depth of 24 inches below slab subgrade. After the slab subgrade soils have soaked, notify this office and schedule appropriate J moisture testing. NOTE: If sufficient moisture is present, flooding will not be required. The. dowels may be deleted, and the footings and slab may be poured monolithically. When the required moisture content has been achieved, place a lo-mil plastic moisture barrier over the 3/8-inch rock and place two inches of clean sand (SE 30 or greater) on top of the plastic. Use #3 reinforcing rods spaced 18 inches on center each way placed one and one-half inches below the top of the slab. All slabs should be a minimum of five inches in thickness. PRELIMINARY SOIL AND GEOTECHNICAL INVESTIGATION PAGE 8 GIBRALTAR STREET, LA COSTA AREA OF CARLSBAD FEBRUARY 20, 1991 This office must be notified to inspect the sand, slab thickness, and reinforcing prior to concrete pour. Provide contraction joints consisting of sawcuts spaced 12 feet on center each way within 72 hours of concrete pour for all interior slabs. The sawcuts must be a minimum of one- half inch in depth and must not exceed three-quarter inch in depth or the reinforcing may be damaged. D. Exterior Slabs (patios, walkways, and driveways) - All exterior slabs (walkways, patios, etc.) must be a minimum of four inches in thickness reinforced with 6x6/l0xlO welded wire mesh placed one and one-half inches below the top of the slab. Driveways must be a minimum of five inches in thickness and reinforced with #3 reinforcing bars spaced 18 inches on center each way placed one and one-half inches below the top of the slab. Use six inches of clean sand (SE 30 or greater) beneath all slabs. Provide contraction joints consisting of sawcuts spaced six feet on center each way within 72 hours of concrete pour. The depths of the sawcuts should be as described in interior slab rein- forcing, item (6) above. Special attention should be given to any "re-entrant" corners and curing practices (during and after concrete pour) to limit cracking. Construction recommendations are given on the enclosed Plate 8. The concrete reinforcement recommendations provided herein should not be considered to preclude the development of shrinkage related cracks, etc.; rather, these recommendations are intended to minimize this potential. If shrinkage cracks do develop, as is expected from concrete, reinforcements tend to limit the propagation of these features. These recommenda- tions are believed to be reasonable and in keeping with the local standards of construction practice. Footing and slab designs provided herein are based upon soil characteristics only and shOuld not supersede more restrictive requirements set forth by the architect or the structural engineer. Please note that minimum requirements set forth by the respective government agencies may also supersede the recommendations provided in this report. E. Retaining Walls 1. Expansive clayey soils should not be used for backfilling of any retaining structure. All retaining walls, including those planned to surround the interior gymnasium, should be PRELIMINARY SOIL AND GEOTECBNICAL INVESTIGATION PAGE 9 GIBRALTAR STREET, LA COSTA AREA OF CARLSBAD FEBRUARY 20, 1991 provided with a 1:1 wedge of granular, compacted backfill measured from the base of the wall footing upward to the finished surface. Retaining walls should be provided with a backdrainage as outlined on the enclosed Plate 9. 2. Lateral active pressures for sandy soils with a minimum friction angle of 30 degrees and assumed drained backfill conditions are provided below. These values may be used for preliminary design estimates only and are to be re-evaluated when the characteristics qf the backfill soils have been determined. Revised recommendations should be anticipated. Passive resistance is also provided. Active Pressure = 53 pcf equivalent fluid pressure, canti- lever, unrestrained walls with 2:1 backfill surface. Active Pressure = 34 pcf equivalent fluid pressure, canti- lever, unrestrained walls with level backfill surface. At Rest Pressure = 53 pcf equivalent fluid pressure, re- strained walls. *Passive Pressure = 421 pcf equivalent fluid pressure, level surface condition. *Note: Because large movements must take place before maximum passive resistance can be developed, the earth pressures given for passive conditions should be reduced by a safety factor of two. j 3. A coefficient of friction of 0.35 may be considered for concrete on soils. This value is to be verified at the completion of grading when the properties of the subgrade soils are specifically known. F. Design - Based upon the nature of on-site soils and the J foregoing recommendations, an allowable bearing value of 1900 pounds per square foot for a 12-inch wide by 24-inch deep footing may be utilized for design purposes. This value applies to dead plus live loads and may be increased by one-third for - wind and seismic loading. j G. Drainage/Erosion Control 1. Excessive moisture can adversely impact the stability of hillside properties. Consequently, finished grades should provide positive drainage away from structures and site slopes. Ponding of surface waters should not be allowed at PRELIMINARY SOIL AND GEOTECHNICAIj INVESTIGATION PAGE 2.0 GIBRALTAR STREET, LA COSTA AREA OF CARLSBAD FEBRUARY 20, 1991 the site. Construction soils should be dispersed in a proper manner that will not interfere with positive drainage flow. Consideration should be given to providing a suitable plant growth upon the graded cut slopes around the north perimeter of the property as a means of controlling surface erosion. Plants should be broad-leafed, deep-rooted types which require minimum irrigation as recommended by the project landscaper. Overwatering of on-site vegetation should be avoided. Only the amount of irrigation necessary to sustain plant growth should be provided. Back-drainage should be provided behind all retaining walls at the project in accordance with the attached Plate 9. Pavement - AC pavement surfaces should only be placed atop granular, non-expansive subgrade soils which have been compacted to 95% of the laboratory standard in the upper 12 inches. Specific pavement designs can best be provided at the completion of rough grading based upon R-value tests of the actual soils. However, for preliminary design purposes, a section of two-inch AC over five inches of compacted Class II base may be utilized for preliminary design purposes. Post grading tests should be conducted to verify this design. Utility Trench Backfill - All underground utility trenches should be compacted to a minimum of 902. of the maximum dry density of the soil unless otherwise specified by the respective agencies. Care should be taken not to crush the utilities or pipes during the compaction of the soil. Non-expansive, granular backfill soils should be used. Plan Review - Final grading and foundation plans should incor- porate recommendations provided in this transmittal and be reviewed and approved by this office. If the final development plans significantly change, or if they were not available at the j time of this investigation, further investigation and subsoil study may be required and should be anticipated. Geotechnical and Construction Inspections - Grading operations should be continuously inspected by the project geotechnical consultant. Testing of fill will assist the contractor to achieve proper moisture and compaction levels. Particular attention should be given to removal operations and drainage installation. PRELIMINARY SOIL AND GEOTECHNICAL INVESTIGATION PAGE Ii. GIBRALTAR STREET, LA COSTA AREA OF CARLSBAD FEBRUARY 20, 1991 Footing excavations and foundation/slab reinforcement s h o u l d also be inspected and approved by the project geotechn i c a l consultant. L. Preconstruction Conference - A preconstruction meeting between representatives of this office and the property owner o r planner, as well as the grading contractor/build e r , i s recommended in order to discuss grading/ construction deta i l s associated with site development. VII. LIMITATIONS The conclusions and recommendations provided herein have b e e n b a s e d on all available data obtained from our field investigat i o n a n d laboratory analyses, as well as our experience with the so i l s a n d formational materials located in the general area. The m a t e r i a l s encountered on the project site and utilized in our labo r a t o r y testing are believed representative of the total are a ; h o w e v e r , earth materials may vary in characteristics between exca v a t i o n s . Of necessity we must assume a certain degree of continuity b e t w e e n exploratory excavations and/or natural exposures. It is n e c e s s a r y , therefore, that all observations, conclusions, and recommen d a t i o n s be verified during the grading operation. In the event discrepancies are noted, we should be contacted immediate l y s o t h a t an inspection can be made and additional recommendations i s s u e d i f required. The recommendations made in this report are applicable t o t h e s i t e at the time this report was prepared. It is the responsibili t y o f the owner/developer to insure that these recommenda t i o n s a r e carried out in the field. It is almost impossible to predict with certainty the f u t u r e performance of a property. The future behavior of the site i s a l s o dependent on numerous unpredictable variables, such as e a r t h q u a k e s , rainfall, and on-site drainage patterns. The firm of MV ENGINEERING, INC. shall not be held responsible f o r changes to the physical conditions of the property such as a d d i t i o n of fill soils or changing drainage patterns which occur s u b s e q u e n t to issuance of this report. This report should be considered valid for a period of o n e y e a r and is subject to review by our firm following tha t t i m e . I f significant modifications are made to your tentative devel o p m e n t plan, especially with respect to the height and location o f c u t and fill slopes, this report must be presented to us for r e v i e w and possible revision. S 1 • PRELIMINARY SOIL AND GEOTECHNICAL INVESTIGATION PAGE 12 GIBRALTAR STREET, LA COSTA AREA OF CARLSBAD PEBRUARY 20, 1991 MV Engineering, Inc. warrants that this report has been prepared • within the limits prescribed by our client with the usual O thoroughness and competence of the engineering profession. No ) other warranty or representation, either expressed or implied, is • included or intended. S Once again, should any questions arise concerning this report, please do not hesitate to contact this office. Reference to our Job #1017-91 will expedite response to your inquiries. I S We appreciate this opportunity to be of service to you. MV ENGINEERING, INC. • fn F.l2.33),.) 1 . I I I P RalphM Vinje 1/RED G41 !g Wt I Aft" 1 !'L~a Y"L.,âL ) %) CEG #980 • RNV/DM/kmh O a:1017-91.pre • 0 • S I i .1 .J • .. i .1 S S APPENDIX "A11 CI . 'oo GEOLOGIC CROSS-SECTIONS DE 80 : - ForrnatIonaIRock(Td) -120 100 PROPOSED GRADE ------------ 80 Formational Rock (Td) A' • 12O PROPOSED GRADE : - - - 100 . Formational Rock (Td) - - -80 S 0 PLATE 2 PRIMARY DIVISIONS GROUP SECONDARY DIVISIONS SYMBOL GRAVELS CLEAN GW Well graded gravels, gravel-sand mixtures, little or no lines. 10 CC 0 MORE THAN HALF GRAVELS (LESS THAN _______ GP Poorly graded gravels or gravel-sand mixtures, little or no lines. OF COARSE 5% FINES) GM Silty gravels, gravel-sand-sill mixtures, non-plastic lines. FRACTION IS GRAVEL Z UJ W Ozr LARGER THAN WITH u.. < (I) NO. 4 SIEVE FINES GC Clayey gravels, gravel-sand-clay mixtures, plastic tines. Ui CD :ri:x SANDS CLEAN SW Well graded sands, gravelly sands, little or no tines. SANDS MORE THAN HALF (LESS THAN SP Poorly graded sands or gravelly sands, little or no lines. OF COARSE 5% FINES) 3 w FRACTION IS SANDS SM Silty sands, sand-sill mixtures, non-plastic tines. CC 0 SMALLER THAN WITH NO. 4 SIEVE FINES SC Clayey sands, sand-clay mIxtures, plastic lines. uj ML Inorganic sills and very line sands, rock hour, silty or clayey line LL L4 SILTS AND CLAYS sands or clayey silts with slight plasticity. CL Inorganic clays of low to medium plasticity, gravelly clays, sandy lean LIQUID LIMIT IS LESS THAN 50% clays, clays. _silty _clays, UJI OL Organic silts and organIc silty clays of low plasticity. MH InorganIc, silts, micaceous or diatomaceous line sandy or silty o SILTS AND CLAYS soils, elastic silts. CH Inorganic clays 01 high plasticity, tat clays. w rLIJZ z o z FL 2 LIQUID LIMIT IS OH GREATER THAN 50% to high Organic clays of medium plasticity, organic silts. HIGHLY ORGANIC SOILS PT Peat and other highly organic soils. GRAIN'SIZES U.S. STANDARD SERIES SIEVE CLEAR SQUARE SIEVE OPENINGS 200 40 10 4 314" 3" 12" SAND GRAVEL I I SILTS AND CLAYS I (COBBLES I BOULDERS FINE MEDIUM COARSE FINE COARSE I RELATIVE DENSITY CONSISTENCY SANDS, GRAVELS AND NON-PLASTIC SILTS BLOWS/FOOT VERY LOOSE 0 - 4 LOOSE 4 -10 MEDIUM DENSE 10-30 DENSE 30-50 VERY DENSE OVER 50 CLAYS AND PLASTIC SILTS STRENGTH BLOWS/FOOT VERY SOFT 0-¼ 0-2 SOFT V4 24 FIRM 1/1'1 4-8 STIFF 1-2 8-18 VERY STIFF 2-4 16-32 HARD OVER 4 OVER 32 Blow count, 140 pound hammer falling 30 Inches on 2 Inch O.D. split spoon sampler (ASTM 0-1586) Unconfined compressive strength per SOILTEST pocket penetrometer CL-700 undisturbed chunk sample 24 = Standard Penetration Test (SPT) (ASTM 0-1 586) with blow counts per 6 inches Eli = disturbed sample = 24 California Sampler with blow counts per 6 inches (3 sand cone test KEY TO EXPLORATORY BORING LOGS Unified Soil Classification System (ASTM D"2487) ZONORRODI ENGINEERING GILBRALTAR STREET NEAR JEREZ COURT, L A C O S T A MV ENGINEERING, INC. PROJECT NO. PLATE KEY 1017-91 3 I S .,l 1 1 TEST PIT 1 FILL i (at): light brown clayey sand mottled, soft to loose. 3, S BEDROCK (Td). sandstone, light colored, loosely cemented upper 2', Dense and well cemented at 5' i .j S 1 rOTAL DEPTH 14' S .1 S 1 S i Si S TEST PIT 2 1 • • clayey includes sandstone • d loose moist fragments. t _ t / . BEDROCK(T siltstone, chocolate brown, fractured firm, with \white I arbonate seams. 5 FILL/TOPSOIL: dark brown clay, moist, stiff. TOTAL DEPTH 5' PLATE 1/4 5! S S TOTAL DEPTH 6' TEST PIT .4 FILL (at): clayey sill light to dark brown, Includes scattered bedrock fragments. moist, loose. 1.5 - TOPSOIL: dark brown clay, moist, soft to stiff. TERRACE DEPOSIT (Ot): brown weathered soft gradational contact above; TOTAL DEPTH 8.5' PLATE #5 H S I i .1 1 .1 TEST PIT 5 FILL .1 (at) brown sandy ala 1 cK (Td): siltotone/sands tone, pale brown, tight, loose. cut by white carbonate seams. I TOTAL DEPTH 5 I .1 . I HI I TEST PIT 6 .1 .J 5 FILL (of): light colored clayey silt, dry, - loose, mottled; 5 BEDROCK (Td): sandstone, tan btQwn, TERRACE DEPOSIT (Qt): brown clay, 5 dry, dense, soft to stiff, with scattered gypsum seams. j • • I TOTAL DEPTH 8' • S . .- PLATE #6 TEST PIT 7 TOTAL DEPTH O BEDROCK (Td): sandstone, Ian brown damp to moist, cemented PLATE #7 RE-ENTRANT CORNER REINFORCEMENT scale. rant Isolation joints around the columns should be either circular as shown in (a) or diamond shaped as shown in (b). If no isolation joints are used around columns, or if the corners of the isolation joints do not meet the contraction joints, radial cracking as shown in (c) may occur (reference Ac t ) . re-entrant corners (±2700 corners), provide Re-entrant corner reinforcement shown herein is provided as a general guideline only and is subject to verification and changes by the project architect and/ o r structural engineer based upon slab geometry, location, and other engineering and construction factors. Plate 118 S II SPECIFICATIONS FOR CALTRANS CLASS II PERI'IEABLE MATERIAL U.S. Standard Sieve Size Z Passing 1" 100 3/4" 90-100 3/8" 40-100 No. 4 25-40 No. 8 18-33 No. 30 5-15 No. 50 0-7 No. 200 0-3 Sand Equivalent 75 *If Caltrans Class II permeable material is used in place of 3I4"-I' gravel, fabric filter may be deleted. **SUBDPJIN TYPE - Subdrain type should be Acrylonitrile Butadiene Stryene (A.B.S.), Polyvinyl Chloride (PVC) or approved equiva- lent. Class 125, SDR 32.5 should be used for maximum fill depths of 35 feet. Class 200, SDR 21 should be used for maximum fill depths of 100 feet. BACK DRAIN DETAIL ..-SEE T-CONNECTION 6 MIN. 7 DETAIL OVERLAP / 3/4'-1-1/2 CLEAN GRAVEL* (310/(1. MIN.) 8' MIN. COVER NON-PERFORATED ER FOR A TED PIPE PIPEAR %-MI M. FILTER FABRIC ENVELOPE (MIRAFI 4' MIN. 140N OR APPROVED BEDDING EQUIVALENT)* SUBDRAIN TRENCH DETAIL PERFORATED 10 MIN. EACH SIDE PIPE CAP OUTLET PIPE T-CONNECTION DETAIL PLATE # 9 APPENDIX "B" 8/88 SPECIFICATIONS FOR CONSTRUCTION OF CONTROLLED FILLS GENERAL DESCRIPTION The following grading specifications have been prepared for the subject site and are consistent with the Preliminary Investigation Report performed by this firm. The grading contractor shall be responsible to perform ground preparation and compaction of fills in strict compliance with the specifications outlined herein. All earthwork including ground preparations, placing, watering, spreading, and compacting of fills should be done under the supervision of a state registered geotechnical engineer. The project geotechnical engineer should be consulted if any deviations from the grading requirements provided herein are desired by the owner/developer. The construction of controlled fills shall consist of clearing and removal of existing structures and foundations, preparation of land to be filled, excavation of earth and rock from cut area, compaction and control of the fill, and all other work necessary to complete the grading of the filled areas to conform with the lines, grades, and slopes as shown on the accepted plans. CLEARING AND PREPARATION OF AREAS TO-BE FILLED All fill control projects shall have a preliminary soil investigation or a visual examination (depending upon requirements of the governing agency and the nature of the job) by a qualified geotechnical engineer prior to grading. All timber, trees, brush, vegetation, and other rubbish shall be removed, piled, and burned, or otherwise disposed of to leave the prepared areas with a finished appearance, free from unsightly debris. Any soft, swampy, or otherwise unsuitable areas shall be corrected by drainage or removal of compressible material, or both, to the depths indicated on the plans and as directed by the geotechnical engineer. The natural ground which is determined to be satisfactory for the support of the proposed fill shall then be plowed or scarified j to a depth of at least six inches (611) or deeper as specified by the geotechnical engineer. The surface should be free from ruts, hummocks, or other uneven features which would tend to prevent uniform compaction by the equipment to be used. 1 No fill shall be placed until the prepared native ground has been approved by the geotechnical engineer or his representat i v e on site. Where fills are made on hillsides with slopes greater than 5:1 (horizontal to vertical), horizontal benches shall be cut in t o firm, undisturbed, natural ground. A minimum two-foot deep keyway, one blade width, should be cut. The geotechnical engineer sh a l l determine the width and frequency of all succeeding benches which will vary with the soil conditions and the steepness of slope. After the natural ground has been prepared it shall be brought to the proper moisture content and compacted to not less than 90% of maximum density per ASTM D-1557-78. Expansive soils may require special compaction specifications as directed in the preliminary soil investigation by the geotechnical engineer. In order to reduce the potential for differential settlement for structures placed on a transition area of the lot, the cut portion. should be undercut a minimum depth of three feet below the prop o s e d pad grade or to a minimum depth of twelve inches below the botto m of the footing, whichever is greater, and replaced as structural fill. The undercut should extend a minimum horizontal distance o f ten feet outside the building perimeter. O 10. Caution should be used during the grading and trench excavations so that existing adjacent or undergrou n d structures/improvements are not distressed by the removals. Appropriate setbacks will be required and should be anticipated. All existing utilities on or in the vicinity of the property sho u l d be located prior to any grading or trenching operations. Th e s e . precautions are the responsibility of the owner/ contractor. MV ENGINEERING, INC. will not be held responsible for any damage or distress. MATERIALS The fill soils shall consist of select materials, graded so tha t at least 40 percent of the material passes the #4 sieve. The material may be obtained from the excavation, a borrow pit, or b y mixing soils from one or more sources. The materials used shall be free from vegetable matter and other deleterious substances . Oversized rocks greater than two feet in maximum diameter should not be included in fills. Rocks greater than 12 inches (1211 ) in diameter should be properly buried ten feet or more below grade, measured vertically. Rocks should be placed per project geotechnical engineer or his representative to assure filling of all voids with compacted soils. Rocks greater than six inches (611) 2 in diameter should not be allowed within the upper three feet of all graded pads. Rock fills require a special inspection and testing program under direct supervision of the project geotechnical engineer or his. representative. If excessive vegetation, rocks, or soils with unacceptable physical characteristics are encountered these materials shall be disposed of in waste areas designated on the plans or as directed by the geotechnical engineer. No material of a perishable, spongy, or otherwise unstable nature shall be used in the fills. If soils are encountered during the grading operation which were not reported in the preliminary soil investigation further testing will be required to ascertain their engineering properties. Any special treatment recommended in the preliminary or subsequent soil reports not covered herein shall become an addendum to these specifications. Laboratory tests should be performed on representative soil samples to be used as compacted fills in accordance with appropriate testing procedures specified by ASTM in order to determine maximum dry density and optimum moisture content of the fill soils. PLACING, SPREADING, AND COMPACTION OF FILL MATERIAL The selected fill material shall be placed in layers which shall not exceed six inches (611) when compacted. Each layer shall be spread evenly and shall be thoroughly blade-mixed during the spreading to insure uniformity of material and moisture in each layer. When the moisture content of the fill material is below that specified by the geotechnical engineer water shall be added until the moisture content is near optimum as determined by the geotechnical engineer to assure thorough bonding during the compaction process. This is to take place even if the proper density has been achieved without proper moisture. When the moisture content of the fill material is above that specified by the geotechnical engineer the fill material shall be aerated by blading and scarifying or other satisfactory methods until the moisture content is near optimum as determined by the geotechnical engineer. After each layer has been placed, mixed, and spread evenly it shall be thoroughly compacted to not less than the recommended minimum compaction requirements per specified maximum density in accordance with ASTM D-1557-78. Compaction shall be by means of tamping or sheepsfoot rollers, multiple-wheel pneumatic-tired rollers, or other types of rollers. Rollers shall be of such design that they will be able to compact the fill to the specified density. Rolling each layer shall be continuous over its entire II area and the rollers shall make sufficient passes to obtain the desired density. The entire area to be filled shall be compacted to the specified density. Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment. Compacting of the slopes shall be accomplished by backrolling the slopes in increments of three to five feet (3 1 - 51 ) in elevation gain or by overfilling and cutting back to the design configuration or other methods producing satisfactory results. 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. Field density tests shall be made in accordance with ASTM Method D-1556-82 by the geotechnical engineer for approximately each foot in elevation gain after compaction, but not to exceed two feet (21 ) in vertical height between tests. The geotechnical engineer shall be notified to test the fill at regular intervals. If the tests have not been made after three feet of compacted fill has been placed, the contractor shall stop work on the fill until tests are made. The location of the tests shall be spaced to give the best possible coverage and shall be taken no farther than 100 feet apart. Tests shall be taken on corner and terrace lots for each two feet (21 ) in elevation gain. The geotechnical engineer may take additional tests as considered necessary to check on the uniformity of compaction. Where sheepsfoot rollers are used, the test shall be taken in the compacted material below the disturbed surface. No additional layers of fill shall be spread until the field density tests indicate that the specified density has been obtained. The fill operation shall be continued in six-inch (611) compacted layers, as specified above, until the fill has been brought to the finished slopes and grades as shown on the accepted plans. SUPERVISION Supervision by the geotechnical engineer or his representative shall be made during the filling and compacting operation in order to verify that the fill was constructed in accordance with the preliminary soil report or agency requirements. The specifications and soil testing of subgrade and basegrade material for roads or other public property shall be done in accordance with specifications of the governing agency unless otherwise directed. 4 It should be understood that the contractor shall supervise and direct the work and shall be responsible for all construction means, methods, techniques, sequences, and procedures. The contractor will be solely and completely responsible for conditions at the job site, including safety of all persons and property during the performance of the work. Intermittent or continuous inspection by the geotechnical engineer is not intended to include review of the adequacy of the contractor's safety measures in, on, or near the construction site. SEASONAL LIMITS No fill material shall be placed, spread, or rolled during unfavorable weather conditions. When the work is interrupted by heavy rain, grading shall not be resumed until field tests by the geotechnical engineer indicate that the moisture content and density of the fill are as previously specified. In the event that, in the opinion of the engineer, soils unsatisfactory as foundation material are encountered, they shall not be incorporated in the grading; disposition will be made at the engineer's discretion. 5 UNIFIED SOIL CLASSIFICATION Identifying Criteria Symbol Soil Description COARSE GRAINED (more than 50% larger than 41200 sieve) Gravels (more than 50% GW Gravel, well-graded gravel- larger than #4 sieve sand mixture, little or no but smaller than 311), fines. non-plastic. GP Gravel, poorly graded, gravel-sand mixture, little or no fines. GM Gravel, silty, poorly graded, gravel-sand-silt mixtures. GC Gravel, clayey, poorly graded, gravel-sand-clay mixtures. Sands (more than 50% SW Sand, well-graded, gravelly smaller than 414 sieve), sands, little or no fines. non-plastic. SP Sand, poorly graded gravelly sand, little or no fines. SM Sand, silty, poorly graded, sand-silt mixtures. SC Sand, clayey, poorly graded, sand-clay mixtures. FINE GRAINED (more than 50% smaller than #200 sieve). Liquid Limit less than 50. ML CL Silt, inorganic silt and fine sand, sandy silt or clayey-silt--sand mixtures with slight plasticity. Clay, inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays. Unified Soil Classification Page 2 FINE GRAINED - continued Liquid Limit greater OL than 50. MH Nil OH HIGHLY ORGANIC SOILS PT Silt, organic, silts and organic silts-clays of low plasticity. Silt, inorganic silts, micaceous or dictoinaceous, fine sand or silty soils, elastic silts. Clay, inorganic, clays of medium to high plasticity, fat clays. Clay, organic clays of medium to high plasticity. Peat, other highly organic swamp soils. LEGEND Existing fill Terrace deposit soils Bedrock/Formational took . Location of test pit Approximate surface contact Cross-Section lines Recommended removal elevation - ' PRELlMtNARY GRADING PLAN -- _- .--- -- .-.-----_ .--- -- ---- "I-. .----- VlCfNllTY MAP/ No SCALE PREPARED BY ZOMORRODI EhGINEERING MARCH 31, 1990 RFFFRFNCF MV FNGlNEERlNQ REPORT DATED FEBRUARY 1991 JOB NO 1017-91 ACE CIVIL ENGINEERING CONSULTING ENGINEERS 7668 EL CAMINO REAL#104-463 CARLSBAD, CA 92009 / EXIST CURB GUTTER 6 SIDEWALK / LEGEND @&ff Existing fill QQ Terrace deposit soils Bedrock/Formational rook . Location of test pit / Approximate surface contact 5 f Cross-Section tines @ Recommended removal elevation V/Ch"t/flTY MAP/ NO SCALE PREPARED BY MARCH 31, 1990 I f<c6!W%z 1 8 ARCHITECTURE 8r PMNING t 1011) WA'Q W4 C%SO, CA 92In ~r~W)~?~ RFFFRFNCF MV FNGINEERINQ REPORT DATED FEBRUARY 1991 JOB NO 1017-91