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HomeMy WebLinkAboutCDP 02-24; ST. CLAIRE RESIDENCE; UPDATE COMPACTION REPORT AND RESPONSE TO THIRD PARTY REVIEW GRADED RESIDENTIAL PAD 4588 ADAMS STREET; 2021-10-18\ID Vinje & Middleton Engineering, Inc. UPDATE COMPACTION REPORT & RESPONSE TO THIRD PARTY REVIEW GRADED RESIDENTIAL PAD 4588 ADAMS STREET CARLSBAD, CALIFORNIA (APN 206-792-38) OCTOBER 18, 2021 Prepared For: Construction Design Management James Chambers Po Box 1571 Solana Beach, Ca 92075 Prepared By: VINJE & MIDDLETON ENGINEERING, INC. 2450 Auto Park Way Escondido, California 92029 Job #21-259-F 2450 Auto Park Way· Escondido, California 92029 · 760-743-1214 · Fax 760-739-0343 TABLE OF CONTENTS PAGE NO. I. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 II. GRADING AND PAD CONSTRUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Ill. SITE CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 IV. PROPOSED CONSTRUCTION ..................................... 2 V. SITE CLASSIFICATION FOR SEISMIC DESIGN ....................... 3 VI. SEISMIC GROUND MOTION VALUE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 VII. CONCLUSIONS AND RECOMMENDATIONS .......................... 4 A. Existing Graded Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 B. Bearing & Subgrade Soil Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 C. Existing Graded Slopes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 D. Remedial Pad Grading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 E. Engineering Observation & Testing .............................. 7 F. Foundations, Sib-on-Grade Floors, & Soil Design Parameters ........ 7 G. Concrete Exterior Flatwork . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 H. Asphalt, PCC Pavement Design & Permeable Interlocking Concrete Pavers . . . . . . . . . . . . . . . . . . . . . . . . . 8 I. Engineering Observation & Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 VIII. RESPONSE TO THIRD PARTY REVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 IX. GENERAL RECOMMENDATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 X. LIMITATIONS .................................................. 12 PLATE NO. Grading Plans Prepared by La Costa Engineering . . . . . . . . . . . . . . . . . . . . . . . . . 1 Tsunami Inundation Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Appendix A: Appendix B: Appendix C: Update Compaction Report U.S. Seismic Design Map Hetherington Engineering, Inc Third Party Review UPDATE COMPACTION REPORT & RESPONSE TO THIRD PARTY REVIEW GRADED RESIDENTIAL PAD 4588 ADAMS STREET CARLSBAD, CALIFORNIA (APN 206-792-38) I. INTRODUCTION The project study property is a graded residential pad originally created in 2005 -2006 under engineering observation and testing services provided by this office. A copy of the most recent grading plans for the site, prepared by La Costa Engineering (Revised 02/15/17), is included as Plate 1. The approximate property coordinates are 33.1473°N latitude and -117.3260°W longitude. Geotechnical engineering observation and compaction testing services for the graded pad were provided by this office periodically between December 28, 2005 through April 11, 2006. Our observations and tests were summarized in an As-Graded Compaction Report dated April 25, 2006. The original site geotechnical study, prior to its current configuration, was also periormed by this office. The following pertinent reports pertaining to the property were reviewed as a part of this effort: 1. Update Compaction Report, Graded Pad, 4588 Adams Street, Carlsbad, California, Job #19-119-F, report dated March 29, 2019. 2. Slope Stability, Near Vertical Temporary Construction Slopes, Existing Contiguous Graded Pads Located at 475 Park Drive and 4488 Adams Street, Carlsbad, California, Job #05-422-F and 05-423-F, letter dated October 28, 2010. 3. As-Graded Compaction Report and Foundation Recommendations for Proposed Single Family Residence Located at 4488 Adams Street, City of Carlsbad Drawing #412-2A, Project #CDP 03-12, Job #05-423-F, report dated April 25, 2006. 4. Geotechnical Update Letter and Grading Plan Review, Proposed Residential Development, 4488 Adams Street, Carlsbad, California (A.P.N. 206-192-38). Job #05-138-P, letter dated January 27, 2005. 5. Preliminary Geotechnical Investigation, Undeveloped Hillside Lots, 4588 Adams Street, Carlsbad, California, Job #02-108-P, report dated February 11, 2002. V!NJE & MmniFI oN ENlilNEEJUNG, INC. • 2450 t\uro Park \Var• Escondido, California 92029~1229 • Phone (760) 743-1214 UPDATE COMPACTION REPORT AND RESPONSE TO THIRD PARTY REVIEW 4588 ADAMS STREET, CARLSBAD, CALIFORNIA OCTOBER 18, 2021 PAGE2 Copies of the preceding can be obtained upon request. Reference 1, the Update Compaction Report (which includes References 2 and 3) is included as Appendix A. The purpose of this effort is to update the previous update report to current applicable codes, and engineering standards. Additional and/or amended recommendations consistent with the requirements of current codes and standards of practice are also provided in the following sections and will supplement or supersede those previously given. We are also in receipt of third party review comments by Hetherington Engineering, Inc. Our responses are provided in a following section. II. GRADING AND PAD CONSTRUCTION Site grading for the existing building pad included the removal and recompaction of existing surficial soils and then added filling to achieve pad grades. Near vertical temporary construction embankments were left on the west, and north sides of the pad limits. Original earthwork operations including preparation of ground receiving fills, keyway development and construction of graded embankments, fill placement, and compaction procedures were completed in substantial conformance with the requirements of California Building Code (CBC), the Standard Specifications for Public Works Construction and the grading ordinances for the City of Carlsbad. Geotechnical engineering observation and testing for the graded pad were performed under the supervision of this office. In our opinion, site excavations, pad development, and graded embankments were constructed in substantial conformance with the project approved grading plans, and are acceptable for their intended use. Ill. SITE CONDITIONS The most recent grading plan (included as Plate 1) is substantially unchanged from the grading plans utilized during site grading in 2005-2006 (Appendix A). Subsequent to the issue of our previous update report in 2019, the graded pad was used to stockpile excess soil generated from grading the adjacent property. Original graded surfaces and embankments are no longer visible. Site conditions prior to the stockpiling are described in Appendix A. IV. PROPOSED CONSTRUCTION Finish grades are expected to be unchanged from the existing pad elevations, and major grade alterations or significant ground modifications are not planned. However, some fine/contour grading and reconditioning of bearing soils will be required. Retaining/basement walls expected to be utilized for ground transitioning. V!NJE & MIDDl LI ON ENG!NEUUNG, INC. • 2450 Auto Park \Vay• Escondido, California 92029-1229 • Phont: (760) 743-121 ,J UPDATE COMPACTION REPORT AND RESPONSE TO THIRD PARTY REVIEW 4588 ADAMS STREET. CARLSBAD, CALIFORNIA OCTOBER 18, 2021 PAGE3 Future planned residential construction is expected to consist of a conventional wood- frame building with block basement garage walls and exterior stucco supported on shallow stiff concrete foundations with stem-walls and slab-on-grade floors, or slab-on-ground with turned-down footings. V. SITE CLASSIFICATION FOR SEISMIC DESIGN The Site Class is based on the average conditions present within 100 feet of the ground surface, and are designated as A-F. Class A is classified as hard rock and Class F as potentially liquefiable or collapsible soils, and is based on shear wave velocity. For the A and B classification, it is preferable to measure the shear wave velocity onsite. Site Classes C, D and E can be determined by seismic methods or typical Standard Penetration Test (SPT-N) results (based on Section 20.4.2 of ASCE 7-16) conducted during drilling. Site Classification is then established based on Table 20.3-1 of ASCE 7-16. Site Class D is typically used conservatively as a default, unless otherwise noted. However, the Building Code does allow the design condition to be estimated by a geotechnical engineer, engineering geologist, or seismologist with knowledge of specific geologic formations and conditions (considering weathering and fracturing). At the project building location, well compacted fills overlie hard crystalline bedrock units. Based on our past experience with similar deposits, Site Class D (Stiff Soil), can be conservatively considered for the project site subsoil profile, unless otherwise noted. VI. SEISMIC GROUND MOTION VALUES Seismic design values were determined as part of this investigation in accordance with Chapter 16, Section 1613 of the 2019 California Building Code (CBC) and ASCE 7 Standard. Presented values are generated using the web-based SEAOC/OSHPD (Structural Engineers Association of America/California's Office of Statewide Health Planning and Development) ground motion calculator. Generated results at the site are summarized in the enclosed Appendix B. Requirements provided below are also applicable and should be incorporated in the project designs where appropriate: 1. Site specific hazard analysis is required (see Section 11.4.8) in accordance with Chapter 21.2 of ASCE 7-16 for structures on Site Class E sites with values of Ss greater than or equal to 1.0g, and structures on Site Class D and E sites with values of S1 greater than or equal to 0.2g. However, the following 3 exceptions are permitted for Equivalent Lateral Force design (ELF) using conservative values of seismic design parameters in lieu of performing a site specific ground motion analysis: V!NJL & MmDLE 1 ON EN(JIN!T!UNc;, lNc. • 2450 Auto Park \Vay• Escondido, California 92029~1229 • Phone (7~0) 743-1214 UPDATE COMPACTION REPORT AND RESPONSE TO THIRD PARTY REVIEW 4588 ADAMS STREET, CARLSBAD, CALIFORNIA OCTOBER 18, 2021 PAGE4 • Structures on Site Class E sites with Ss greater than or equal to 1.0, provided the site coefficient Fa is taken as equal to that of Site Class C. • For structures on Site Class D sites with S1 greater than or equal to 0.2, a long period coefficient (Fv) of 1.7 may be utilized for calculation of Ts, provided that the value of Seismic Response Coefficient (Cs) is determined by Equation (12.8- 2) for values of the fundamental period of the building (T) less than or equal to 1.5Ts, and taken as 1.5 times the value computed in accordance with either Equation 12.8-3 for T greater than 1.5 Ts and less than or equal to TL or Equation 12.8-4 for T greater than TL. • Structures on Site Class E sites with S1 greater than or equal to 0.2, provided that T is less than or equal to Ts and the equivalent static force procedure is used for the design. 2. Where Site Class B is recommended, and a site specific measurement is not provided, the site coefficients Fa, Fv, and FPGA shall be taken as unity (1.0) in accordance to Section 11.4.3 of ASCE 7-16. 3. Where Site Class D is selected as the default site class per Section 11.4.3 of ASCE 7-16, the value of Fa shall not be less than 1.2. Where the simplified procedure of Section 12.4 is used, the value of Fa shall be determined in accordance with Section 12.14.8.1, and the values of Fv, SMS and SM1 need not to be determined. VII. CONCLUSIONS AND RECOMMENDATIONS The site is characterized by graded surfaces underlain by a minimum of 3 feet of well- compacted fills placed under engineering observation and compaction testing services provided by this office. The current grading plan remains substantially unchanged from plans used for the As-Graded Compaction report, dated April 25, 2006 (Appendix A). Site graded surfaces are currently mantled by stockpiles soil that will be exported. All conclusions and recommendations provided in the previous update report remain valid and should be incorporated into the final plans and implemented during the construction phase except where specifically amended or superseded below. Additional site-specific conclusions and recommendations consistent with the current codes, standards and engineering practice are also provided below and should be considered wherever appropriate and as applicable: V!NJE & MmDLEI UN ENCilNEE!UNCi, INC • 2450 Amo Park \\'ay • Escondido, California 92029-1229 • Phone (760) 743~1214 UPDATE COMPACTION REPORT AND RESPONSE TO THIRD PARTY REVIEW 4588 ADAMS STREET. CARLSBAD, CALIFORNIA OCTOBER 18, 2021 PAGES A. Existing Graded Surfaces: The construction of the graded surfaces, including the temporary construction slopes, was completed in substantial conformance with the specifications of project Preliminary Geotechnical Investigation report (Reference 5, dated February 11, 2002), approved grading plan, applicable codes, standards and ordinances, and are suitable for the support of the planned new structure, provided our recommendations are followed. B. Bearing and Subgrade Soil Properties: Bearing and subgrade soils predominantly consist of silty clayey sand (SM/SC) soils ranging to very low expansion potential (expansion index less than 20) based on ASTM D-4829 classification. Consequently, expansive soils are not considered a significant geotechnical concern C. Existing Graded Slopes: Project graded slopes are currently covered by stockpiled soil. All graded slopes should be evaluated after exporting of the excess covering material, with recommendations provided at that time. Care should be taken during exporting to not remove portions of the previous graded embankments. D. Remedial Pad Grading: New graded pad modifications are not anticipated. Final design grades are expected to be at or very near the existing grades. However, near finish grade soils at the graded pad surfaces have experienced continued seasonal wetting and drying since the completion of original grading more than 15 years ago. Consequently, after removal of the stockpiled soil, minor remedial grading of near surface soils and bearing / subgrade soils will be required in order to recondition the upper bearing and subgrade soils and reconstruct suitable surfaces for the support of the planned new residential structure and improvements. The following are appropriate: 1. All excavations, removals or stripping, grading, earthwork, construction, and bearing/subgrade soil preparation should be completed in accordance with Chapter 18 (Soils and Foundations) and Appendix "J" (Grading) of the 2019 California Building Code (CBC), ASCE 7-16, the Standard Specifications for Public Works Construction, City of Carlsbad Grading Ordinances, the requirements of the governing agencies and following sections, wherever appropriate and as applicable. VJNJL & M!l)DLETON ENC!NLL!UNG, I Ne. • 2450 Amo Park \Vay• Escondido, California 92029-1229 • Phone (760) 743-1214 UPDATE COMPACTION REPORT AND RESPONSE TO THIRD PARTY REVIEW 4588 ADAMS STREET, CARLSBAD, CALIFORNIA OCTOBER 18, 2021 PAGE6 2. Compacted fills should be stripped (removed) to a minimum depth of 2 feet below existing surfaces, or as directed in the field, and recompacted in all areas of planned new buildings, structures and improvements. Stripping and recompaction should encompass building and improvement envelopes plus a minimum of 5 horizontal feet outside the perimeter, where possible and as approved in the field. Actual striping depths to be established in the field by the project geotechnical consultant or his designated field representative. Locally deeper removals may be required based upon actual exposures, and should be anticipated. 3. Site soils generated from the site removals and over-excavations are considered suitable for reuse as new site fills provided they are adequately processed and manufactured into a clean uniform mixture as directed and approved in the field. Gravelly fill deposits typically require additional processing, mixing and moisture conditioning efforts in order to manufacture a uniform homogeneous mixture suitable for reuse as new compacted fills. 4. Uniform and stable fill support should be constructed underneath the project new building pad and improvement areas by the remedial grading and earthwork operations. For this purpose, site soils should be adequately processed, thoroughly mixed, moisture conditioned to approximately 2%-3% ( or as directed in the field) above the optimum moisture levels, placed in thin (6-inch lifts maximum) uniform horizontal lifts and mechanically compacted to a minimum of 90% of corresponding laboratory maximum dry density per ASTM D-1557, unless otherwise specified. 5. Trench and wall backfill materials should consist of sandy soils adequately processed, moisture conditioned to near optimum levels and mechanically compacted to a minimum of 90% compaction levels (per ASTM D-1557), unless otherwise specified or directed in the field. 6. All remedial grading, foundation bearing and subgrade soil preparation and earthwork operations including removals and over-excavations, trenching, the suitability of earth deposits used as compacted fills and backfills, processing, spreading and placement, and compaction procedures should be observed and tested by the project geotechnical consultant and presented in the daily field reports and summarized in a final report. The nature of finished bearing and subgrade soils should be further confirmed in the final report at the completion of the remedial grading work. ViNJL & MmnLEH)~ ENGINITR!N(J, INC. • 2450 Auto Park \Vay• Escondido, California 92029-1229 • Phone (760) 743-1214 UPDATE COMPACTION REPORT AND RESPONSE TO THIRD PARTY REVIEW 4588 ADAMS STREET, CARLSBAD, CALIFORNIA OCTOBER 18, 2021 PAGE7 E. Engineering Observation and Testing: All excavations, remedial grading, new fill placement, wall backfill, foundation bearing and subgrade soil preparation, and earthwork operations should be observed and tested by the project geotechnical consultant and presented in the daily field reports and summarized in a final report. The nature of finished bearing and subgrade soil should be further confirmed in the final report at the completion of the remedial grading work. F. Foundations, Slab-on-Grade Floors, and Soil Design Parameters: Soil design parameters and foundation recommendations will remain the same as specified in Appendix A. • All interior slabs should be a minimum 4 inches in thickness, reinforced with #3 reinforcing bars spaced 18 inches on center each way, placed mid-height in the slab. Slabs should be underlain by 4 inches of clean sand (SE 30 or greater) which is provided with a well-performing moisture barrier/vapor retardant (minimum 15-mil Stego) placed mid-height in the sand. Alternatively, slabs may be underlain by a 4-inch thick base of 1 /2-inch or larger clean aggregate provided beneath the slab with a capillary break (vapor barrier) that is in direct contact with concrete, and a concrete mix design which will address bleeding, shrinkage, and curling. The vapor barrier should consist of a minimum 15 mil stego complying with ASTM E1745 Class A requirements and installed in accordance with ASTM E1643, including a proper perimeter seal. G. Concrete Exterior Flatwork: The following are appropriate for exterior concrete improvements. • Exterior Concrete Flatwork: Exterior concrete flatwork (walkways and patios) should be a minimum of 4-inches in thickness reinforced with #3 reinforcing bars spaced 16-inches on center each way, carefully placed 1 ½-inches below the top of the slab. The slab subgrade soils should be compacted to minimum 90% compaction levels at the time of fine grading and before placing the slab reinforcement. • In order to enhance performance of exterior slabs and flatwork a minimum 8 inch wide by 8 inch deep thickened edge reinforced with a minimum of 1-#4 continuous bar near the bottom should be considered along the slab perimeter. Tying the slab panels to adjacent curbs, where they occur, with #3 bars at 16 inches on centers, may also be considered. \'JNJE & Mmnrr!UN EN(i!NLER!N(l, INC.• 2450 Auto Park\Vay • Escondido, California 92029-1229 • Phone (760) 743-1214 UPDATE COMPACTION REPORT AND RESPONSE TO THIRD PARTY REVIEW 4588 ADAMS STREET, CARLSBAD, CALIFORNIA OCTOBER 18, 2021 PAGES • Reinforcements lying on subgrade will be ineffective and shortly corrode due to lack of adequate concrete cover. Reinforcing bars should be correctly placed extending through the construction joints tying the slab panels. In construction practices where the reinforcements are discontinued or cut at the construction joints, slab panels should be tied together with minimum 18 inch long #3 dowels (dowel baskets) at 16 inches on center placed mid-height in the slab (9 inches on either side of the joint). • Provide "tool joint" or "softcut" contraction/control joints spaced 1 O feet on center (not to exceed 12 feet maximum) each way. The larger dimension of any panel shall not exceed 125% of the smaller dimension. Tool or cut as soon as 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 ¾-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 equipment across cuts for at least 24 hours. • Joints shall intersect free-edges at a 90° angle and shall extend straight for a minimum of 1 ½ feet from the edge. The minimum angle between any two intersecting joints shall be 80°. Align joints of adjacent panels. Also, align joints in attached curbs with joints in slab panels. Provide adequate curing using approved methods (curing compound maximum coverage rate= 200 sq. ft./gal.). H. Asphalt, PCC Pavement Design and Permeable Interlocking Concrete Pavers (PICP): Driveway and parking area recommendations remain as outlined in Appendix A. I. Engineering Observation & Testing -This office is to be notified no later than 2 p.m. on the day before any of the following operations begin, in order to schedule appropriate testing and/or observation/documentation: 1. Foundation and Utility Trenches Beneath Building Slab: a) Observe the plumbing trenches beneath slabs after the pipes are laid and prior to backfilling. b) Test the plumbing trenches beneath slabs for minimum compaction requirements prior to sand and moisture barrier placement. VJNJE & MnHH El oN ENG!:-JLEIUNG, INC. • 2450 Auto Park \Vay• Escondido, California 92029~1229 • Phone (760) 743-1214 UPDATE COMPACTION REPORT AND RESPONSE TO THIRD PARTY REVIEW 4588 ADAMS STREET, CARLSBAD, CALIFORNIA OCTOBER 18, 2021 PAGE9 c) Obse,ve the bottom of the foundation trenches for proper embedment into firm compacted fills, and record proper footing width prior to placement of reinforcing steel. d) Inspect footing reinforcement size and placement. Inspect slab thickness and reinforcement, and verbify sand thickness and vapor barrier placement and thickness under the slab, prior to concrete pour. 2. Grading -Improvements -Utility Trenches, Etc.: a) Fill placed under any conditions 12 inches or more in depth, to include: • Building pads. • Street improvements, sidewalks, curbs and gutters. • Utility trench backfills. • Retaining wall backfills. • The spreading or placement of soil obtained from any excavation (spoils from footings, underground utilities, swimming pools, etc.). b) Obseivation and testing of the base layer and subgrade soils beneath driveways, patios, sidewalks, etc., prior to placement of pavement or concrete. c) Moisture testing. d) Any operation not included herein which requires our testing, obseivation, or documentation for submittal to the appropriate agencies. VIII. RESPONSE TO THIRD PARTY REVIEW Hetherington Engineering, Inc. conducted at third party review of the project with their comment letter dated September 16, 2021. A copy of their review letter is included as Appendix C. Based on their review letter, Hetherington Engineering was not provided all the reports pertinent to the project. Their references included our Preliminary Report dated February 11, 2002 (Reference 5), current grading plans (Plate 1) and Slope Stability letter dated October 28, 2010 (Reference 2). Consequently, some of Hetherington's comments are no longer applicable. Our responses are provided in the same order as listed by the reviewer: \'JNJE & Mmrn.ETON EN,:;JNEL!UNtl, INC.• 2450 Auto Park\Vay • Escondido, California 92029-1229 • Phone (760) 743-1214 UPDATE COMPACTION REPORT AND RESPONSE TO THIRD PARTY REVIEW 4588 ADAMS STREET, CARLSBAD, CALIFORNIA 1. This report. OCTOBER 18, 2021 PAGE 10 2. Grading has been completed and no new modifications are expected (Appendix A). Foundation plans are not yet available. 3. N/A 4. N/A 5. N/A 6. See Appendix A. 7. As shown on a Tsunami Inundation Map included as Plate 2, the site is sufficiently removed from the Aqua Hedionda lagoon and Pacific Ocean, making a Tsunami or Seiche impacting the site remote. 8. Grading has been completed. New construction is not expected to impact adjacent property. 9. N/A 10. After bearing soil reconditioning, post construction settlement is expected to be within the acceptable tolerances and are anticipated to be less than approximately 1-inch occurring below the heaviest loaded footing(s). The magnitude of post construction differential settlement of site fill deposits, as expressed in terms of angular distortion, is not anticipated to exceed ½-inch in a distance between similarly loaded adjacent structural elements, or a maximum distance of 20 feet. 11. See Appendix A. 12. See Appendix A and this report. IX. GENERAL RECOMMENDATIONS 1. The minimum steel reinforcement provided herein is based on soil characteristics only, and is not intended to be in lieu of reinforcement necessary for structural considerations. \'JNJE & Mmnu: 1 nN ENCi!Nff!U~c;, }NC. • 2450 Auto Park \Vay• Escondido, California 92029~1229 • Phone (760) 743-1214 UPDATE COMPACTION REPORT AND RESPONSE TO THIRD PARTY REVIEW 4588 ADAMS STREET, CARLSBAD, CALIFORNIA OCTOBER 18, 2021 PAGE 11 2. 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 recommendations are believed to be reasonable and in keeping with the local standards of construction practice. Special attention should be given to any "re-entrant" corners (±270 degree corners - Appendix A) and curing practices during and after concrete pour in order to further minimize shrinkage cracks. 3. It should be noted that the characteristics of as-compacted fill may change due to post-construction which can results from cycles of drying and wetting, water infiltration, environmental factors, etc. These changes can cause detrimental changes in the fill soil properties such as strength capacity, compressibility characteristics, volume change behavior, permeability, etc. 4. 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. The features depend chiefly upon the condition of concrete and weather conditions at the tome of construction and do not reflect detrimental ground movement. Hairline stucco cracks will often develop at windows/door corners, and floor surface cracks up to 1/s-inch wide in 20 lineal feet may develop as a result of normal concrete shrinkage (according to the American Concrete Institute). 5. The amount of shrinkage related cracks that occur in concrete slab-on-grades, flatwork 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: a. Use the stiffest mix that can be handled and consolidated satisfactorily. b. Use the largest maximum size of aggregate that is practical, for example concrete made with %-inch maximum size aggregate usually requires about 40- pounds (nearly 5 gallons) more water per cubic yard than concrete with 1-inch aggregate. c. Cure the concrete as long as practical. VJNJE & Mmrn E"J nN ENCilNUJUNll, INC:. • 2450 Auto Park \Vay• Escondido, California 92029-1229 • Phone (760) 743-1214 UPDATE COMPACTION REPORT AND RESPONSE TO THIRD PARTY REVIEW 4588 ADAMS STREET, CARLSBAD, CALIFORNIA OCTOBER 18, 2021 PAGE12 6. 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. 7. All retaining walls should be provided with a drain along the backside as generally shown on the "Retaining Wall Drain" detail enclosed with Appendix A. Specific drainage provisions behind retaining wall structures should be inspected by this office prior to backfilling the wall. All backfill soils must be mechanically compacted to a minimum of 90% of the corresponding maximum dry density, ASTM 0-1557. The planting of large trees behind any retaining wall will adversely affect their performance and should be avoided. Expansive 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. 8. All underground utility trenches beneath interior and exterior slabs 12-inches or more in depth shall be compacted by mechanical means 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 trench backfill. Trench backfill materials and compaction shall also conform to the requirements of governing agencies and authorities, as applicable. Non-expansive, granular backfill soils should be used. Flooding or jetting of the backfill is not allowed. X. LIMITATIONS Our description of grading operations, as well as observation and testing services, have been limited to those grading operations performed periodically from October 7, 2005 through March 31, 2006. The conclusions contained herein have been based upon our observation and testing as noted. No representations are made as to the quality or extent of materials not observed and tested. This report is issued with the understanding that the owner or his representative is responsible to ensure 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 are provided with a copy of this report and carry out recommendations specified therein during the construction. VJNJL & MIDDi unN ENGJNELJUNG. INC.• 2450 Auto Park\Vay • Escondido, California 92029-1229 • Phone (760) 743-1214 UPDATE COMPACTION REPORT AND RESPONSE TO THIRD PARTY REVIEW 4588 ADAMS STREET. CARLSBAD, CALIFORNIA OCTOBER 18, 2021 PAGE13 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 soil engineer should also be provided the opportunity to field verify the foundations prior to placing concrete. If the project geotechnical 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 permit purposes for a period of six months and is subject to review by our firm following that time. In case of plan revisions including changes in the final pad size, 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. If you have any questions or need clarification, please contact this office at your convenience. Reference to our Job #21-259-F will help to expedite our response to your inquiries. We appreciate this opportunity to be of service to VINJE & MIDDLETON ENGINEERING, INC. Steven J. Melzer CEG #2362 V!NJE & M!PDi E rnN ENGIN!TR!NCi, INc. • 2450 Auto Park \Vay• Escondido, C:ilifornia 92029~1229 • Phone (760) 743-1214 REFERENCES Annual Book of ASTM Standards, Section 4 -Construction, Volume 04.08: Soil and Rock (I); D420 - D5876, 2016. Annual Book of ASTM Standards, Section 4 -Construction, Volume 04.09: Soil and Rock (II); D5877 - Latest, 2016. Corrosion Guidelines, Caltrans, Version 1.0, September 2003. California Building Code (CBC), California Code of Regulations Title 24, Part 2, Volumes 1 & 2, 2016, International Code Council. "The Green Book" Standard Specifications For Public Works Construction, Public Works Standards, Inc., BNi Building News, 2015 Edition. California Geological Survey, 2008 (Revised). Guidelines for Evaluating and Mitigating Seismic Hazards in California, Special Publication 117 A, 108p. California Department of Conservation, Division of Mines and Geology (California Geological Survey), 1986 (revised), Guidelines for Preparing Engineering Geology Reports: DMG Note 44. California Department of Conservation, Division of Mines and Geology (California Geological Survey), 1986 (revised), Guidelines to Geologic and Seismic Reports: DMG Note 42. "Proceeding o!The NCEER Workshop on Evaluation of Liquefaction Resistance Soils," Edited byT. Leslie Youd and lzzat M. Idriss, Technical Report NCEER-97-0022, Dated December 31, 1997. "Recommended Procedures For lrnplernentation of DMG Special Publication 117 Guidelines For Analyzing and Mitigation Liquefaction In California," Southern California Earthquake center; USC, March 1999. "Foundations & Earth Structures," Naval Facilities Engineering Command, DM 7.02. "Introduction to Geotechnical Engineering, Robert D. Holtz, William D. Kovacs. "Introductory Soil Mechanics and Foundations: Geotechnical Engineering," George F. Sowers, Fourth Edition. "Foundation Analysis and Design," Joseph E. Bowels. Caterpillar Performance Handbook, Edition 29, 1998. "An Engineering Manual For Slope Stability Studies," J.M. Duncan, A.L. Buchignani and Marius De Wet, Virginia Polytechnic Institute and State University, March 1987. "Minimum Design Loads For Buildings and Other Structures," ASCE 7-10, American Society of Civil Engineers (ASCE). USGS Maps http://ngmdb.usgs.gov/maps/mapview/, 2016b. SEAOC/OSHPD (Structural Engineers Association of America/ California's Office of Statewide Health Planning and Development) ground motion calculator https:1/seisrnicmaps.org/ 0 ' ~ 0 !. ; I II) 0 'I I -'\I' I I J I ... ~ '; I. / J /' :J o ' 1 I I I I • I .._ 1 1. I I I ,,, I .._ ~ 'i I / / I ! I !EXIST. 075 BRciN DITCH ._Ci I , / / / , I SYSTEM PER G"'°'NG PU\N PARCEL 1 MAP 12773 SAME OWNER NOT-A-PART PROPOSED I). 75 T'l'PE B BROW DITCH v-PROPERTY UNE l,PAD•71.~I' ---~•72 0 llr5111\JCT. RET. WAU. I •1 , ~ I ..:---tL......1.:d..2. ·-·"'tu.......'!!. __ J_ l &_s~~ I --SOUO LINE REPRESENTS FINISHED G~E ................... 1 ___ _ J 1 -I I I -.. 0 #, .'I, 1 1 1 ; , 1owc. ◄23-BB,JPARCEL r, YM.10119 :1 1 I I I i . I ' I I I ., .. DASHED LINE REPRESENTS EXISTING co11om0Ns/-L ,• ,f I I /;'. I I I I, / 1 I I I CD EXIST!~ 5.0.G.E EASEMENT -1 11---,✓ ✓ CROSS SECTION E -~ ~ I I I ; RECOR~ED 10-16-~1 BOOK -. ,--~ ~ I I I , PAGE J15, w101H Nlor GIi/Di I r ,-~ L I ,' 1 / I , / 1 _I r I I · ~--.!f'll_2!:_J2"t / I / \. [I I , 1 I I ' . ~ , I / Fl,80.6 " : , · 1 , 1 · ,-, ..,. _Joo.of' 7 I\· .. I I I I / i I -,._ ..,_ ~' . I . r I I I · l J , I ~,._ I I I/ I I .. ,, I I f' :v I I '1 / I I f / ,·: 1, 1' I ' I I I I I 1 1 I · ' / / / f/., I : I \' R£0UIR£D ~AT PRESERvAl10N , / / t;:1/S / '/ 1 / 20~L(92-38 / ~ ill"' ;. I I t ' I PARCEL 1 1 / 1 ,I< / / / ~ ,' M1P / 1_0178 / l , t ~ I I v~. 50' F.iflf: BUFFER ~ 1 I ' / ' I I "'·'. I I / I I ii .:i ~-, N/£XIST. 16°-24"H U RET. 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PER!.IEABLE PAYERS ◄" CONC CYWr I ' EDGE RESTRAIITT / ·, 2"--5,:_ 10%--_"i:.J:;~l.,..1:~~z....,1.~1.,,~~ ls:1~r:~-r~:£'j;:i~=c_, ==_=_==:L ,/ \1, ,, ' ,, ' ~· .,., J • ... , . ......., . ~/) '"J -' l"-i!. .,, ' .0 ~ ·, ', • l· - 2• BEDDING COU~SE ASTl,I NO B OR NO 9 AGGR~TES IN OPENINGS PER lo'ANUrACTURER SPECS ' SOIL SUBG~E, UPPER 8" OPEN GRADED BASE, 12" CO!.IPACTED TO 95,r; AST!.I N0.57 STONE ', ' / ', 1' // SECTION AT OWY PERMEABLE PAVERS \., ,/,,,:.~,, ~ /' /"q.(1-';,.~" > /¢-'Q_,,~" EXISTING RECIPROCAL ACCE'SS@ / _,,~ ,,~" 'AND DRIVEWAY ANO UTILITY ,, /r.,:S-'~/ MAINTENANCE AGR££MENT / ~ ~ 11ETWEEH PARCEL 1 MAP 10175 , ,,~,..:.,✓-- AND PARCEL I or MAP 10118_/ ~ ~,,. EASEMENTS PER DOC. 1993-0◄3l760 ,r {}_·,, _ _-;1, ____________________ _ ~ , / ,,~.,,. ~ CD EXISTING S.O.G.E. EASEMENT RECORDED 10-16-◄I. , . ~,, r7' ,t-BOOK 1252 PAGE 315. SEE RECORD OF SURVEY 14183 ' ~ pt;\'-WIDlH OF TOTAL EASEMENT NOT GIi/Di. WIDlH OF / / / "fl EASEME'IIT ONTO 26-192-38 GIVEN AS 1.28'. ~ ,, .,. .,. ~ ~ ACCESS RIGHTS Ci RANTED TO THE OWNER or PARCEL 2 1,~~ElPSTIN~-:SHARfll' G~-l◄C ... ,. {I) or WJ> 10178 B'I' THE OWNER OF PARCEL I WJ> 10178 I· "x" l1R~1 APPRDAC~~ PER WJ> 10178. ::{,c-t ,,,. ,,.,,. ~-,, /'· ~'l / r<i-@ EXISTING RECIPROCAL ACCESS ANO DRIVEWA'I' ANO UTILITY ; / ,,.~ MAIIITENANCE AGREEME'IIT BETWEEN PARCEL I MAP 10175 '\v,,~" f ,i, EXISTING 10· \/CP SE'WER ANO PARCEL I or MAP 10178 PER DOC. 1993-0431760, NOT TO SCAU'. ABBREVIATIONS TW • FINISH GRADE AT TOP or WALL ew -FINISH GRADE AT BOTTO!.I OF' WALL HP ~ HIGH POINT Ff • FINISH f'I.OOR ELEVATION Gr • GARAGE FINISH FlOOR IE • INVERT ELEVATION CONC. • CONCRETE SPECS. PER SOILS EIIGI REQUIREMENTS Fl • FlOWUtolE ELEVATION 1G • TOP OF GRATE ELEVATION "AS BUILT' ~ PER DWG 149-8 © NOT PLOffiD. EASEME'IIT RECORDED APRIL 11, 1944 IN ,, · EXISllllG 10· ACP WATER ~g<TIJ~5~t~: mr.:: oirn~~ ~~:~· .~ / ER DWG 149-8 IIOT DISCLOSED IN PUBLIC RECORDS. RCE: __ _ E'XP, ___ _ DATE " ,. / '1/~' 'v / @ EXISTING 10' SDG&E EASE!.IENT RECORDED 10-8-86. §'a FILE NO, 85-452761. 'Y. / ,,. NC RE:VIE'wED ev, INSPECTOR DATE ~,," IN ,.. I -7~,,/ ~ /$ -:.:/ ,,f .,,. ~ fsiFrl CITY-OFCARLSBAD t-1--11i---1i---------------11i---+1---1---111--tl ~ p~N~N~ERJNG DEPARTHE'NT Adams St. SFR ISH4 ;'"~ ,,,,. ~// ~~ /ol' .. 4588 Ad:ims S1rcc1. C:irlsb3d Ca 92008 GR2021- t---1--+---------------+--lf--+--lf---l jAPPROVED: JASON S. GELOEI TSUNAMI INUNDATION MAP * Map Legend Tsunami Inundation Line Scale: 1 : 12,000 Tsunami Inundation Area Excerpt from the Tsunami Inundation Map for Emergency Planning, Oceanside Quadrangle/San Luis Rey Quadrangle, June 1, 2009. Plate 2 V &M Job #21-259-F Appendix A UPDATE COMPACTION REPORT GRADED PAD 4488 ADAMS STREET CARLSBAD, CALIFORNIA March 29, 2019 Prepared For: Jim Chambers P.O. Box 1571 Solana, Beach, CA 92075 Prepared By: VINJE & MIDDLETON ENGINEERING, INC. 2450 Auto Park Way Escondido, California 92029 Job #19-119-F TABLE OF CONTENTS PAGE NO. I. INTRODUCTION ...................................................... 1 II. GRADING PAD CONSTRUCTION ••.........•.....••....•..•..•..•.....•.. 2 Ill. SITE CONDITIONS .••.•........•...•..•••............••....••.•....••. 2 IV. PROPOSED CONSTRUCTION .....••..••••......•••..•..••.....•.••..••. 3 V. SEISMIC GROUND MOTION VALUES ..............••••..••.....•.••.....• 3 VI. REGIONAL GEOLOGY ......••...••.••....•.•....•..•.................• 4 VII. CONCLUSIONS AND RECOMMENDATIONS ................................ 4 A. Existing Graded Surfaces •.••...••.•......•......•....•......•.••..•• 5 8. Bearing and Subgrade Soil Properties .•••...•••....•.•....•••.....•.... 5 C. Existing Graded Slopes •......••......•.......•.••..••.......•....••• 5 D. Existing Surface Conditions .......••.•...••....•......•.•......•....• 5 E. Remedial Pad Grading ....•••......••......•..•.•.••......•..•..•.•.. 5 F. Engineering Observation and Testing ...•.•....•......••.••..••........ 7 G. Site Corrosion Assessment ...•..••......•.......•............•••••.• 7 H. Temporary Construction Slopes .......•••.•..••.....•.••....•.......•. 7 I. Foundations, Slab-on-Grade, Floors, and Soil Design Parameters ....•..•.•.• 7 J. Asphalt and PCC Pavement Design ...•.•.•..••....•......•.•.......... 9 K. Slope Planting and Drainage ..•.•....•.•.......•....••.........•...• 12 L. Pad Drainage .........•.......•..•.....••....••.....•.••..•••..... 13 M. Additional Engineering Observation and Testing .......•............•.•. 13 VIII. GENERAL RECOMMENDATIONS ....................................... 14 IX. LIMITATIONS .•......•......•••..•...••.....•......••......••.....••. 16 PLATE NO. Vicinity Map ......••..•..........••......•....................•........••.. 1 Parcel Map ................................................................ 2 Graded Building Pad ..••.......•....•.•..............•...•..........•..•..•. 3 Geologic Map ..••.....•.......••......•..•...••.............••............. 4 Isolation Joints & Re-Entrant Corner Reinforcement ..........••......•....•...... 5 Typical Permeable Paver Detail ..............••.....•......•...•...•........•• 6 Retaining Wall Drain Detail .........••................................•.....•. 7 Attachments: Slope Stability letter dated October 28, 2010, As-Graded Compaction Report dated April 25, 2006, and USGS Summary report. I. INTRODUCTION UPDATE COMPACTION REPORT GRADED PAD 4488 ADAMS STREET CARLSBAD, CALIFORNIA The project property, reference above, includes a graded pad originally created in late 2005 and early 2006 under observation and testing services provided by this office. The property location is indicated on a Vicinity Map attached as Plate 1. The approximate property coordinates are 33.1473°N latitude and -117.3260°W longitude. The building pad consists of split level graded surfaces. The lower garage pad (approximate elevation 62 MSL) is marked by near vertical temporary slopes along the north and west pad margins. The upper pad (approximate elevation 71.5 MSL) is adjacent to the northern end of the lower pad with a large soil stockpile currently occupying the location. Both the lower and upper pads were created by placing fill atop formational rock deposits. Geotechnical engineering observation and compaction testing services for the graded pad was provided by this office periodically between December 28, 2005 through April 11, 2006. Our observations and tests were summarized in a written technical report. The original site geotechnical study prior to its development was also performed by this office. The following pertinent reports and letter pertaining to the property are on file with our firm and were reviewed as a part of this effort: A. Slope Stability, Near Vertical Temporary Construction Slopes, Existing Contiguous Graded Pads Located at 475 Park Drive and 4488 Adams Street, Carlsbad, California, Job #05-422-F and 05-423-F, letter dated October 28, 2010. B. As-Graded Compaction Report and Foundation Recommendations for Proposed Single Family Residence Located at 4488 Adams Street, City of Carlsbad Drawing #412-2A, Project #CDP 03-12, Job #05-423-F, report dated April 25, 2006. C. Geotechnical Update Letter and Grading Plan Review, Proposed Residential Development, 4488 Adams Street, Carlsbad, California (A.P.N. 206-192-38), Job #05-138-P, letter dated January 27, 2005. E. Preliminary Geotechnical Investigation, Undeveloped Hillside Lots, 4588 Adams Street, Carlsbad, California, Job #02-108-P, report dated February 11, 2002. Copies of the preceding can be obtained upon request. The Slope Stability letter (Reference A) and As-Graded Compaction Report and Foundation Recommendations (Reference B) are included as Attachments 1 and 2 respectively. UPDATE COMPACTION REPORT-GRADED PAD 4488 ADAMS STREET, CARLSBAD. CA MARCH 29, 2019 PAGE2 The purpose of this effort is to update the referenced As-Graded Compaction Report and Foundation Recommendations (Attachment 2) and confirm its compatibility with the current applicable codes, and engineering standards. Additional and/or amended recommendations consistent with the requirements of current codes and standards of practice are also provided in the following sections and will supplement or superseded those given in the referenced As-Graded Compaction Report and Foundation Recommendations where specifically indicated. A recent site visit was also conducted by our engineering geologist on March 18, 2019 as a part of the preparation of this update report. Added subsurface explorations and laboratory testing were not necessary, and prior geotechnical data (see references) were determined to be adequate for this update report. II. GRADING AND PAD CONSTRUCTION The current building pads were created by the removal and recompaction of existing surficial soils and then continue filling to achieve pad grades. Temporary construction embankments mark the west, and north sides of the lower graded garage area. Earthwork operations including preparation of ground receiving fills, keyway development & construction of graded embankments, fill placement, and compaction procedures were completed in substantial conformance with the requirements of California Building Code (CBC), the Standard Specifications for Public Works Construction and the grading ordinances for the City of Carlsbad. Grading control engineering observation and testing were performed under the supervision of this office. In our opinion, site excavations, pad development, and graded embankments were constructed in substantial conformance with the project approved grading plans, and are acceptable for their intended use. Ill. SITE CONDITIONS An excerpt from the As-Graded Compaction Report plan is included as Plate 2. Our recent site inspection indicated that the subject site remains substantially unchanged from those reported in the referenced Slope Stability letter (Reference A) and As-Grade Compaction Report (Reference 2) with respect to the site graded conditions, compacted fills, final pad elevation, and location and height of temporary construction slopes. UPDATE COMPACTION REPORT -GRADED PAD 4488 ADAMS STREET, CARLSBAD. CA MARCH 29, 2019 PAGE3 The temporary slopes generally approach 1 O feet high maximum at near vertical gradients. The slopes were constructed in substantial conformance with our recommendations presented in the Preliminary Geotechnical Investigation (Reference E). Construction was expected to proceed in a timely manner, consequently, the slopes have been exposed to nearly 13 years of seasonal conditions. This has resulted in slope face erosion that can be seen on a picture of the pad area taken on March 18, 2019 and attached as Plate 3. However, the slopes are considered grossly stable with no evidence of deep-seated instability. Clearing and brushing of the site surface vegetation and remedial grading of upper near surface exposures of disturbed and weathered pad grade soils will be required as specified in following sections. IV. PROPOSED CONSTRUCTION Final grades are expected to remain at or very near the existing pad elevations, and major grade alterations or significant ground modifications are not anticipated. We understand that the new structure will have a basement garage floor approximately 1 O feet below upper pad grades. Consequently, basement type retaining walls are anticipated to be incorporated into the design. The planned residential construction is expected to consist of a conventional wood-frame building with block basement garage walls and exterior stucco supported on shallow stiff concrete foundations with stem-walls and slab-on-grade floors, or slab-on-ground with turned-down footings. V. SEISMIC GROUND MOTION VALUES Seismic ground motion values were determined as part of this investigation in accordance with Chapter 16, Section 1613 of the 2016 California Building Code (CBC) and ASCE 7-10 Standard using the web-based SEAOC/OSHPD (Structural Engineers Association of America/California's Office of Statewide Health Planning and Development) ground motion calculator. Generated results including the Mapped (Ss. S1), Risk-Targeted Maximum Considered Earthquake (MCER) adjusted for site Class effects (SMs, SM1), and Design (Sos, So1) Spectral Acceleration Parameters. Also included are Site Coefficients {Fa, Fv) for short periods (0.2 second and 1 second), Site Class, Design and Risk-Targeted Maximum Considered Earthquake (MCER) Response Spectrums, Mapped Maximum Considered Geometric Mean (MCEG), Peak Ground Acceleration adjusted for Site Class effects (PGAM) and Seismic Design Category based on Risk Category. The severity of the design earthquake ground motion at the site are summarized in the enclosed Attachment 3. UPDATE COMPACTION REPORT -GRADED PAD 4488 ADAMS STREET. CARLSBAD, CA VI. REGIONAL GEOLOGY MARCH 29, 2019 PAGE4 The project site is situated at the western margin of the Peninsular Ranges Geomorphic Province of southern California. This geomorphic province encompasses an area that extends for approximately 790 miles, from the Transverse Ranges and the Los Angeles Basin to the tip of Baja California, and varies in width from 30 to 100 miles. In general, the Peninsular Ranges consist of rugged mountains underlain by Mesozoic era (67 to 245 million years old) metamorphic and crystalline rocks to the east and a dissected coastal plain underlain by Cenozoic era (up to 67 million years old) sediments. The mountain ranges of this geomorphic province are generally northwest-trending and separated by subparallel fault zones, and are largely composed of granitic and related rocks and smaller amounts of metamorphic rocks. The coastal portions of this geomorphic province in the San Diego region are typically comprised of marine and non-marine sedimentary rocks that have been deposited within a northwest-trending basin known as the San Diego Embayment. The Peninsular Ranges are bounded on the east by the Salton Trough and on the north by the Los Angeles Basin, and extends westward into the Pacific Ocean where its highest peaks are exposed at Catalina, Santa Barbara, San Clemente, and San Nicholas Islands. The Peninsular Ranges are traversed by several major active faults. Right-lateral, strike-slip movement is the major tectonic activity associated with faults in the regional tectonic framework. Earthquakes along these faults have the potential for generating strong seismic ground motions in the region. The seismic event most likely to affect the planned residential development would be a major earthquake on the Rose Canyon Fault. The Rose Canyon Fault is a complex zone of strike-slip, oblique, reverse, and normal faults that extend onshore from La Jolla Cove south to San Diego Bay, and is capable of generating a magnitude-7.2 earthquake. A Geologic Map showing mapped units at, and nearby the project site is included as Plate 4. VII. CONCLUSIONS AND RECOMMENDATIONS The site is characterized by nearly level-graded pads ranging from lower garage surfaces to an upper pad, both underlain by a minimum of 3 feet of well-compacted fills placed under engineering observation and compaction testing services provided by this office. The site remains substantially unchanged from conditions presented in the referenced As- Graded Compaction report, dated April 25, 2006 (Attachment 2) and Slope Stability letter (Attachment 2) dated October 10, 2010. Gross instability is not in evidence. All conclusions and recommendations provided in the referenced As-Graded Compaction report remain valid and should be incorporated into the final plans and implemented during the construction phase except where specifically amended or superseded below. Additional site-specific conclusions and recommendations consistent with the current codes, standards and engineering practice are also provided below and should be considered wherever appropriate and as applicable: UPDATE COMPACTION REPORT-GRADED PAD 4488 ADAMS STREET. CARLSBAD. CA MARCH 29, 2019 PAGES A. Existing Graded Surfaces: The construction of the graded surfaces, including the temporary construction slopes, was completed in substantial conformance with the specifications of project Preliminary Geotechnical Investigation report (dated February 11, 2002), approved grading plan, applicable codes, standards and ordinances, and are suitable for the support of the planned new structure, provided our recommendations are followed. B. Bearing and Subgrade Soil Properties: Bearing and subgrade soils predominantly consist of silty clayey sand (SM/SC) soils ranging to very low expansion potential (expansion index less than 20) based on ASTM D-4829 classification. Consequently, expansive soils are not considered a significant geotechnical concern C. Existing Graded Slopes: Project graded and temporary slopes are generally performing well. Temporary slopes evidence variable stages of erosion and local slumping, however, are considered grossly stable. D. Existing Surface Conditions: Surface areas are presently covered by grass and weeds. All the surface vegetation should be cleared and properly disposed offsite. E. Remedial Pad Grading -Added cut or fill grading efforts or significant ground modifications are not anticipated with final design grades expected to be at or very near the existing grades. However, near finish grade soils atthe project building pad surfaces have experienced continued seasonal wetting and drying since the completion of original grading nearly 13 years ago. Consequently, minor remedial grading of near surface soils and bearing and subgrade soils will be required in order to recondition the upper bearing and subgrade soils and reconstruct suitable surfaces for the support of planned new structures and improvements. The following are appropriate: 1. All excavations, removals or stripping, grading, earthwork, construction, and bearing/subgrade soil preparation should be completed in accordance with Chapter 18 (Soils and Foundations) and Appendix "J" (Grading) of the 2016 California Building Code (CBC), the Standard Specifications for Public Works Construction, City of Carlsbad Grading Ordinances, the requirements of the governing agencies and following sections, wherever appropriate and as applicable. UPDATE COMPACTION REPORT-GRADED PAD 4488 ADAMS STREET, CARLSBAD, CA MARCH 29, 2019 PAGE& 2. Compacted fills should be stripped (removed) to a minimum depth of 2 feet, or as directed in the field and recompacted, in all areas of planned new building, structures and improvements. Stripping and recompaction should encompass building and improvement envelopes plus a minimum of 5 horizontal feet outside the perimeter, where possible and as approved in the field. Actual striping depths to be established in the field by the project geotechnical consultant or his designated field representative. Locally deeper removals may be required based upon actual exposures, and should be anticipated. 3. Silty clayey soils generated from the site removals and over-excavations are generally considered suitable for reuse as new site fills provided they are adequately processed and manufactured into a clean uniform mixture as directed and approved in the field. Clayey to silty fill deposits typically require additional processing, mixing and moisture conditioning efforts in order to manufacture a uniform homogeneous mixture suitable for reuse as new compacted fills. Expansive clayey soils, if present, are not suitable for garage wall and trench backfills. 4. Uniform and stable fill support should be constructed underneath the project new building pad and improvement areas by the remedial grading and earthwork operations. For this purpose, site soils should be adequately processed, thoroughly mixed, moisture conditioned to approximately 3% to 5% (or as directed in the field) above the optimum moisture levels, placed in thin (6-inch lifts maximum) uniform horizontal lifts and mechanically compacted to a minimum of 90% of corresponding laboratory maximum dry density per ASTM D-1557, unless otherwise specified. 5. Trench backfill materials should consist of sandy soils adequately processed, moisture conditioned to near optimum levels and mechanically compacted to a minimum of 90% compaction levels (per ASTM D-1557), unless otherwise specified or directed in the field. 6. All remedial grading, foundation bearing and subgrade soil preparation and earthwork operations including removals and over-excavations, trenching, the suitability of earth deposits used as compacted fills and backfills, processing, spreading and placement, and compaction procedures should be observed and tested by the project geotechnical consultant and presented in the daily field reports and summarized in a final report. The nature of finished bearing and subgrade soils should be further confirmed in the final report at the completion of the remedial grading work. UPDATE COMPACTION REPORT -GRADED PAD 4488 ADAMS STREET, CARLSBAD. CA MARCH 29, 2019 PAGE7 F. Engineering Observation and Testing: All excavations, remedial grading, new fill placement, foundation bearing and subgrade soil preparation, and earthwork operations should be observed and tested by the project geotechnical consultant and presented in the daily field reports and summarized in a final report. The nature of finished bearing and subgrade soil should be further confirmed in the final report at the completion of the remedial grading work. G. Site Corrosion Assessment: Results of limited laboratory testing performed on selected site soil samples (see corrosion section of Attachment 2) indicated that the project site is non-corrosive. Portland cement Type II and concrete with minimum specified 28 days compressive strength (fc) of 2,500 psi and maximum water- cement ratio of 0.50 should be considered, unless otherwise specified (also see CBC Table 1808.8.1). H. Temporary Construction Slopes: All temporary construction slopes are generally performing adequately, but will require geotechnical inspections during the construction operations. 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. Appropriate permits for offsite grading or excavation encroachments into neighboring private properties and/or public right-of-ways, if any required or necessary, should be obtained as appropriate from respective owners and agencies. I. Foundations, Slab-on-Grade Floors, and Soil Design Parameters: Soil design parameters will remain the same as specified in the referenced As-Graded Compaction Report and Foundation Recommendations (Attachment 2). The proposed building may be supported on shallow stiff concrete grade beam footings and slab-on-grade floor foundations consistent the anticipated underlying bearing and subgrade soil. Final foundation bearing and subgrade soils are expected to consist of either sandstone or a silty clayey sand mixture (SM/SC) with expansion potential ranging from to very low expansive (expansion index less than 20 based on ASTM D-4829 classification). Added or modified recommendations may also be necessary and should be given at the time of foundation plan review phase. All foundations and floor slab recommendations should be further confirmed and I or revised as necessary at the completion of rough grading based on the actual expansion characteristics of the foundation bearing and subgrade soils. UPDATE COMPACTION REPORT -GRADED PAD 4488 ADAMS STREET, CARLSBAD, CA MARCH 29, 2019 PAGES The following recommendations and geotechnical mitigation are appropriate for stiff grade beam footings and slab-on-grade type foundation support: • Perimeter and interior continuous footings should be sized at least 15 inches wide and 18 inches deep for single and two story buildings. Spread pad footings, if any, should be at least 30 inches square and 12 inches deep. Footing depths are measured from the lowest adjacent ground surface, not including the sand/gravel layer beneath floor slabs. Continuous interior and exterior foundations should be reinforced with a minimum of four #4 reinforcing bars. Place two-#4 bars 3 inches above the bottom of the footing and two-#4 bars 3 inches below the top of the footing. Reinforcement details for spread pad footings should be provided by the project architect/structural engineer. • All interior slabs should be a minimum 4 inches in thickness, reinforced with #3 reinforcing bars spaced 18 inches on center each way, placed mid-height in the slab. Slabs should be underlain by 4 inches of clean sand (SE 30 or greater) which is provided with a well-performing moisture barrier/vapor retardant (minimum 15-mil Stego) placed mid-height in the sand. Alternatively, a 4-inch thick base of compacted ½-inch clean aggregate provided with the vapor barrier (minimum 15-mil Stego) in direct contact with (beneath) the concrete may also be considered provided a concrete mix which can address bleeding, shrinkage and curling is used • Provide "softcut" contraction/control joints consisting of sawcuts spaced 10 feet on center each way for all interior slabs. 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 sawcuts should be minimum 1-inch in depth but should not exceed 1 ¼- inches deep maximum. 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. • Provide re-entrant corner (270 degrees corners) reinforcement for all interior slabs. Re-entrant corners will depend on slab geometry. The enclosed Plate 5 may be used as a general guideline. UPDATE COMPACTION REPORT -GRADED PAD 4488 ADAMS STREET. CARLSBAD. CA MARCH 29, 2019 PAGES • The subgrade and foundation bearing soils should not be allowed to dry prior to pouring the concrete or additional ground preparation and moisture reconditioning will be necessary as directed in the field. The required moisture content of the bearing soils is approximately 2% to 3% over the optimum moisture content to the depth of 18 inches below subgrade. Attempts should be made to maintain as-graded moisture contents in order to preclude the need for additional subgrade and bearing soil moisture reconditioning and preparation work. • 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 steel reinforcement or concrete pour. J. Asphalt and PCC Pavement Design: 1. Asphalt Concrete (AC) Paving: 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 initial planning phase and cost estimating purposes only (not for construction): • A minimum section of 4 inches of asphalt concrete (AC) on 6 inches Caltrans Class 2 aggregate base (AB) or the minimum structural section required by City of Carlsbad, whichever is more, may be considered for the onsite asphalt paving surfaces outside the private and public right-of-way. Actual designs will depend on final subgrade R-value and design Tl, and the approval of the City of Carlsbad. • In the areas where the longitudinal grades exceed 10%, ½-inch asphalt concrete should be added to the design asphalt concrete thickness for each 2% increase in grade or portion thereof. PCC paving should be considered for longitudinal grades over 15%. • Maximum lift for asphalt concrete shall not exceed 3 inches, unless otherwise approved. The asphalt concrete layer (4-inch total section) may consist of 2.5 inches of a binder/base course (¾-inch aggregate) and 1.5 inches of finish top course (½-inch aggregate) topcoat, placed in accordance with the applicable local and regional codes and standards. UPDATE COMPACTION REPORT-GRADED PAD 4488 ADAMS STREET. CARLSBAD, CA MARCH 29, 2019 PAGE10 • The Class 2 aggregate or recycled base (AB) materials shall meet or exceed the requirements set forth in the current California Standard Specification (Caltrans Section 26-1.02). Aggregate base (AB) materials should be compacted to a minimum 95% of the corresponding maximum dry density (ASTM D-1557). Subgrade soils beneath the asphalt paving surfaces should also be compacted to a minimum 95% of the corresponding maximum dry density within the upper 12 inches. 2. PCC Paving: Residential PCC paving supported on very low expansive subgrade soil should be a minimum 5½ inches in thickness, reinforced with #3 reinforcing bars at 15 inches on center each way, placed at mid-height in the slab. Subgrade soils beneath the PCC paving should be compacted to a minimum 90% of the corresponding maximum dry density. Reinforcing bars should be correctly placed extending through the construction (cold) joints tying the slab panels. In construction practices where the reinforcements are discontinued or cut at the construction joints, slab panels should be tied together with minimum 18-inch long (9 inches on either side of the joint) #3 dowels placed at the same spacing as the slab reinforcement. In order to enhance performance, tying of the slab panels to the adjacent curbs, gutters and improvements, where they occur, with #3 dowels at 15 inches on center maximum may also be considered. Additionally, enhanced performance of PCC pavement can be achieved by providing a minimum 8 inch wide by 8 inch deep thickened edge, reinforced with a minimum of one-#3 continuous bar near the bottom, along the slab perimeter. Provide "tool joint" or "softcut" contraction/control joints spaced 1 0 feet on center (not to exceed 15 feet maximum) each way. The larger dimension of any panel shall not exceed 125% of the smaller dimension. Tool or cut as soon as the slab will support the 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 in depth but should not exceed 1 ¼-inches deep maximum. In case of softcutjoints, anti-ravel skid plates should be used and replaced with each blade to avoid spalling and ravelings. Avoid wheeled equipments across cuts for at least 24 hours. Joints shall intersect free edges at a 90° angle and shall extend straight for a minimum of 1 ½ feet from the edge. The minimum angle between any two intersecting joints shall be 80 °. Align joints of adjacent panels. Also, align joints in attached curbs with joints in slab panels. Provide adequate curing using approved method (curing compound maximum coverage rate= 200 sq. ft./gal.) UPDATE COMPACTION REPORT-GRADED PAD 4488 ADAMS STREET. CARLSBAD. CA MARCH 29, 2019 PAGE11 3. Permeable Interlocking Concrete Pavers (PICP): Permeable Interlocking Concrete Pavers (PICP), if considered as a part of the project stormwater quality treatment BMPs, should consist of a self-contained system disallowing saturation of adjacent foundation bearing soil, wall backfill, natural/graded embankments, and site improvement subgrade. In general, PICP pavement should maintain a minimum clear distance of 3 feet from building foundations with finish subgrade sloped away at a minimum 2% into a 12 inch wide collector trench along the low edge that is provided with a 4-inch diameter (Sch. 40 or SDR 35) underdrain pipe surrounded with ¾-inch crushed rocks, as conceptually shown in the enclosed Typical Permeable Paver Detail, Plate 6. In case of nearby fill embankments and wall backfill, a minimum 1 O feet clear setback should be considered, unless otherwise approved. The perforated underdrain pipe should discharge collected water into an appropriate storm drainage facility Perimeter cutoff walls and curb restraints should be provided, and bottom and sides of the system lined with an impervious liner, as shown. PICP pavement closer than 3 feet to building foundations (or 10 feet from adjacent retaining walls or top of slope) may also be allowed, however additional mitigation measures such as construction of a minimum 8 inch wide, 3-sack concrete cutoff wall extending a minimum of 24 inches below bottom of the foundation or adjacent improvements may be required, unless otherwise approved. More specific recommendations should be provided by the project geotechnical consultant at the final plan review phase. The PICP pavement structural section should consist of 31/e-inch, PICP over a minimum of 2 inches of ASTM No. 8 bedding course/choke stone over a minimum 8 inches of ASTM No. 57 stone base course over a minimum of 12 inches of 95% compacted subgrade (per ASTM D-1557). Bedding course/choke stone and base course stone should also be well compacted, consolidated and interlocked (avoid crushing the underdrain pipes) with heavy construction equipments. ASTM No. 8, No. 9 or No. 89 should be used for joint materials depending on the joint size and per manufacturer recommendations. Gradation requirements for ASTM No. 57 , No. 8, No. 89 and No. 9 are as follows: UPDATE COMPACTION REPORT-GRADED PAD 4488 ADAMS STREET. CARLSBAD, CA MARCH 29, 2019 PAGE 12 TABLE 1 -··~ --· .. -Sieve --Percent Passlna1 -I Size ·----~ -- No, 57 _ No. B. -~ . No. 89 I No. 9 . • • C 1½" 100 1" 95 to 100 ½" 25 to 60 100 100 1/e" 85 to 100 90 to 100 100 No.4 Oto 10 10 to 30 20 to 55 85 to 100 No. 8 Oto 5 o to 10 5 to 30 10 to 40 No.16 Oto 5 Oto 10 Oto 10 No. 50 Oto 5 0 to 5 4. General Paving: Base section and subgrade preparation, 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. Curb and gutters and sidewalks supported on potentially expansive subgrade soils should also be provided with a minimum of 4 inches of Caltrans Class 2 base or 6 inches of Green Book Class 3 D.G. base, unless otherwise approved. Base layer under curb and gutters should be compacted to a minimum 95%, while subgrade soils under curb and gutters, and base and subgrade under sidewalks should be compacted to a minimum 90% compaction levels. Appropriate recommendations should be given in the final as-graded compaction report. Base and subgrade soils_ should be tested for proper moisture and specified compaction levels, and approved by the project geotechnical consultant prior to the placement of the base or asphalUPCC/PICP finish surface. K. Slope Planting and Drainage: All slopes should be landscaped with types of plants and planting that do not require excessive irrigation. Excess watering of slopes should be avoided. Slopes left unplanted will be subject to erosion. The irrigation system should be installed in accordance with the governing agencies. UPDATE COMPACTION REPORT-GRADED PAD 4488 ADAMS STREET. CARLSBAD, CA MARCH 29, 2019 PAGE 13 Water should not be allowed to flow over the slopes in an uncontrolled manner. Until landscaping is fully established, plastic sheeting should be kept accessible to protect the slopes from periods of prolonged and/or heavy rainfall. Berms should be constructed along the top edges of all fill slopes. In no case should water be allowed to pond or occur in a concentrated flow condition or flow over graded slopes. L. Pad Drainage: The owner/developer is responsible to insure that adequate measures are taken to properly finish grade the building pad after the structures and other improvements are in place so that the drainage waters from the improved site and adjacent properties are directed away from proposed structures in accordance with the designed drainage patterns shown on the approved plans. A minimum of 2% gradient should be maintained away from all foundations. Roof gutters and downspouts should be installed with all discharge water from the downspouts directed away from the foundations and slab to a suitable location. Area drains should be installed in the yards to collect surface water. Planter areas adjacent to foundations should be provided with damp/water proofing, using an impermeable liner against the footings, if determined appropriate. A subdrainage system within the planter area may also be necessary in some cases to prevent saturations of the foundation soils. It should be noted that shallow groundwater conditions may still develop in areas where no such conditions existed prior to site development. This can be contributed to by substantial increases of surface water infiltration resulting from landscape irrigation which was not present before the development of the site. It is almost impossible to absolutely prevent the possibility of shallow groundwater on the entire site. Therefore, we recommend that shallow groundwater conditions be remedied if and when they develop. The future property owner should be made aware that altering drainage patterns, landscaping, the addition of patios, planters, and other improvements, as well as over irrigation and variations in seasonal rainfall, all affect subsurface moisture conditions, which in turn affect structural performance. M. Additional Engineering Observation and Testing: This office is to be notified no later than 2 p.m. on the day before any of the following operations begin, in order to schedule appropriate testing and/or observation/documentation: 1. Foundations and Utility Trenches Beneath Building Slabs: a) Observe the plumbing trenches beneath slabs after the pipes are laid and prior to backfilling. UPDATE COMPACTION REPORT-GRADED PAD 4488 ADAMS STREET. CARLSBAD. CA MARCH 29, 2019 PAGE 14 b) Test the plumbing trenches beneath slabs for minimum compaction requirements prior to sand and moisture barrier placement. c) Observe the bottom of the foundation trenches for proper embedment into well-compacted fills, and record proper footing width prior to placement of reinforcing steel. d) Inspect footing reinforcement size and placement. Inspect slab thickness and reinforcement, and verbify sand thickness and vapor barrier placement and thickness under the slab, prior to concrete pour. 2. Grading -Improvements -Utility Trenches, Etc.: a) Fill placed under any conditions 12 inches or more in depth, to include: • Building pads. • Street improvements, sidewalks, curbs and gutters. • Utility trench backfills. • Retaining wall backfills. • The spreading or placement of soil obtained from any excavation (spoils from footings, underground utilities, swimming pools, etc.). b) Observation and testing of the base layer and subgrade soil beneath driveways, patios, sidewalks, etc., prior to placement of pavement or concrete. c) Moisture testing. d) Any operation not included herein which requires our testing, observation, or documentation for submittal to the appropriate agencies. VIII. GENERAL RECOMMENDATIONS 1. The minimum steel reinforcement recommended is based on soil characteristics only, and is not intended to be in lieu of reinforcement necessary for structural considerations. UPDATE COMPACTION REPORT -GRADED PAD 4488 ADAMS STREET. CARLSBAD. CA MARCH 29, 2019 PAGE 15 2. 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 recommendations are believed to be reasonable and in keeping with the local standards of construction practice. Special attention should be given to any "re-entrant" corners (±270 degree corners) and curing practices during and after concrete pour in order to further minimize shrinkage cracks. 3. It should be noted that the characteristics of an as-compacted fill may change due to post-construction which can results from cycles of drying and wetting, water infiltration, environmental factors, etc. These changes can cause detrimental changes in the fill soil properties such as strength capacity, compressibility characteristics, volume change behavior, permeability, etc. 4. 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. The features depend chiefly upon the condition of concrete and weather conditions at the tome of construction and do not reflect detrimental ground movement. Hairline stucco cracks will often develop at windows/door corners, and floor surface cracks up to 1/e-inch wide in 20 lineal feet may develop as a result of normal concrete shrinkage (according to the American Concrete Institute). 5. The amount of shrinkage related cracks that occur in concrete slab-on-grades, flatwork 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/e-inch maximum size aggregate usually requires about 40- pounds (nearly 5 gallons) more water per cubic yard than concrete with 1-inch aggregate. • Cure the concrete as long as practical. UPDATE COMPACTION REPORT-GRADED PAO 4488 ADAMS STREET, CARLSBAD, CA MARCH 29, 2019 PAGE16 6. 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. 7. All retaining walls should be provided with a drain along the backside as generally shown on the Retaining Wall Drain Detail (included as Plate 7). Wall backdrains should be inspected and approved by this office prior to wall backfill operations. Expansive soils should not be used for backfilling of any retaining structure. All retaining walls should also be provided with a 1 :1 wedge of granular, compacted backfill measured from the base of the wall footing to the finished surface. The planting of large trees behind any retaining wall will adversely affect their performance and should be avoided. 8. All underground utility trenches beneath interior and exterior slabs 12-inches or more in depth shall be compacted by mechanical means 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 trench backfill. Trench backfill materials and compaction shall also conform to the requirements of governing agencies and authorities, as applicable. Non-expansive, granular backfill soils should be used. Flooding or jetting of the backfill is not allowed. IX. LIMITATIONS Our description of grading operations, as well as observation and testing services, have been limited to those grading operations performed periodically from October 7, 2005 through March 31, 2006. The conclusions contained herein have been based upon our observation and testing as noted. No representations are made as to the quality or extent of materials not observed and tested. This report is issued with the understanding that the owner or his representative is responsible to ensure 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 are provided with a copy of this report and carry out recommendations specified therein during the construction. UPDATE COMPACTION REPORT-GRADED PAD 4488 ADAMS STREET, CARLSBAD, CA MARCH 29, 2019 PAGE 17 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 soil engineer should also be provided the opportunity to field verify the foundations prior to placing concrete. If the project geotechnical 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 permit purposes for a period of six months and is subject to review by our firm following that time. In case of plan revisions including changes in the final pad size, 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. If you have any questions or need clarificationt please contact this office at your convenience. Reference to our Job #19~119-F will help to expedite our response to your inquiries. We appreciate this opportunity to be of service to you. VINJE & MIDDLETON ENGINEERING, INC. REFERENCES Annual Book of ASTM Standards, Section 4 -Construction, Volume 04.08: Soil and Rock (I); D420 - D5876, 2016. Annual Book of ASTM Standards, Section 4 -Construction, Volume 04.09: Soil and Rock (II); D5877 - Latest, 2016. Corrosion Guidelines, Caltrans, Version 1.0, September 2003. California Building Code (CBC), California Code of Regulations Title 24, Part 2, Volumes 1 & 2, 2016, International Code Council. "The Green Book" Standard Specifications For Public Works Construction, Public Works Standards, Inc., BNi Building News, 2015 Edition. California Geological Survey, 2008 (Revised), Guidelines for Evaluating and Mitigating Seismic Hazards in California, Special Publication 117 A, 108p. California Department of Conservation, Division of Mines and Geology (California Geological Survey), 1986 (revised), Guidelines for Preparing Engineering Geology Reports: DMG Note 44. California Department of Conservation, Division of Mines and Geology (California Geological Survey), 1986 (revised), Guidelines to Geologic and Seismic Reports: DMG Note 42. "Proceeding of The NCEER Workshop on Evaluation of Liquefaction Resistance Soils," Edited by T. Leslie Youd and lzzat M. Idriss, Technical Report NCEER-97-0022, Dated December 31, 1997. "Recommended Procedures For Implementation of DMG Special Publication 117 Guidelines For Analyzing and Mitigation Liquefaction In California," Southern California Earthquake center; USC, March 1999. "Foundations & Earth Structures," Naval Facilities Engineering Command, DM 7.02. "Introduction to Geotechnical Engineering, Robert D. Holtz, William D. Kovacs. "Introductory Soil Mechanics and Foundations: Geotechnical Engineeringt George F. Sowers, Fourth Edition. "Foundation Analysis and Design," Joseph E. Bowels. Caterpillar Performance Handbook, Edition 29, 1998. "An Engineering Manual For Slope Stability Studies," J.M. Duncan, AL. Buchignani and Marius De Wet, Virginia Polytechnic Institute and State University, March 1987. "Minimum Design Loads For Buildings and Other Structures," ASCE 7-10, American Society of Civil Engineers (ASCE). USGS Maps http://ngmdb.usgs.gov/maps/mapview/. 2016b. SEAOC/OSHPD (Structural Engineers Association of America/ Cafifornia's Office of Statewide Health Planning and Development) ground motion calculator https://seismicmaps.org/ 1 PACIFIC 0~ STATE BEACH 2 3 2006 Thomas Bros. Ma s E F PROJECT SITE: 1106 -G7 l VICINITY MAP J 1 (7 -,a /i;; l.£GO£NI) \\ CAl/11.WNJA ~ ~ 2 1150 2300 3 • J ( PLATE 1 ) V&M JOB #19-119-P Ii I I I I l , , '/'II/ I .I ; //11111 // //////// / / "I I I ~\ I I / / I / I I I I I I / / -~AIAE ou,liiVJ't.l .. ,' iFE'£ 11..0.:fJt-R~1-' ' ' i l :-~~J• r1 ~'ER NO T'AP:4RT 1' I / P. 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PER CMWD . jf;' _ I ~ r ~ ~~<t, iANDARD § _ // ~"' WG W3 ,,ff!~ /1 ~ -y' ~~ //.r:--" ,,, / /' ,V ~., ~ -~z ;./ .·) / I ~ _,,, ~ -1· ,,, I/ G);;(r. ;::---,#· .. i / / / /,.'/14, ' -,✓_ • Graded Building Pad 4488 Adams Street, Carlsbad Looking North From Driveway (3/18/2019) Plate 3 V&M Job #19-119-F GEOLOGIC MAP Pertinent Geologic Deposits D Qop:z-4 Old Paralic Deposits (Late to Middle Pleistocene). D Tsa Santiago Formation (Middle Eocene) Excetpt From the Geologic Map of the Oceanside 30' x 60' Quadrangle, California Michael P. Kennedy and Siang S. Tan, 2006. Scale 1 :25,000 Plate 4 V&M Job #19-119-F ISOLATION JOINTS & RE-ENTRANT CORNER REINFORCEMENT (A) RE-ENTRANT CORNER REfNFORCEMENT --. No. 4 BARS PLACED AT 1.5" '- BELOW TOP OF SLAB NOTES: Typical -No Scale (B) (C) 1. Isolation joints around the columns should be either circular as shown in (A) or diamond shaped as shown in (B). Ifno isolation joints are used around comlwnns, or if comers of the isolation joints do no meet the contraction joints, radial cracking as shown in (C) may occur (Reference ACI). 2. In order to control cracking at the re-entrant corners ( +270° corners), provide reinforcement as shown in (C). 3. Re-entrant coner reinforcement shown is provided as a general guideline only and is subject to verification and changes by the project architect or structural engineer based upon slab geometry, location. and other engineering and construction factors. VINJE & MIDDLETON ENGINEERING, INC. 2450 Auto Parle Way Escondido, California 92029 760-743-1214 vinjc.middleton@sbcglobal.net PLATES V&M Job #19-119-F Jwy 2018 I TYPICAL PERMEABLE PA VER DETAIL I Not To Scale ASTM No. 8 or No. 9 Aggregates in opening Per Manufactures Specifications 3 ½ " Thick Concrete Pavers Curb/ Concrete Edge Restraint (Min. 6") 2" Bedding Course ASTM No. 8 or No. 9 Aggregate or Per Manufactures Specifications • <I •. 4 Drain Subgrade · : B" Thick Open Graded Base to Perforated Pipe (ASTM No. 57 Stone) in.2%- :111111111 1111111111 111 11 I" '111' "I _)II~ 11~,w, 11~ 116" =------11 1==1I1-111 111-lJl-W:==N ,:_ ~ t Ill i' Ill Ill 11111 1111 Ii' llj II Ii' I Ill i' 1111 { ·= Ill I I I i' 11m™ I i' II II I I ,~L__!____!_-I ill-ill .. 1 lmpenneable Liner: HOPE or PVC Geomembrane 4" Perforated Underdrain (Sch. 40) Surrounded with¾" Rock Slope to drain (Min. 30 Mil Thick) '---Soil Subgrade Upper 12" Compacted to 95% (ASTM D1557) Vinje & Middleton Engineering, Inc. Plate 6 V & M Job #19-119-F RETAINING WALL DRAIN DETAIL Typical -No Scale Waterproofing V V V V V V vvvvv vvvv Drain e Approved Compacted Soil or Competent Natural Material CONSTRUCTION SPECIFICATIONS: ---Filter material. Crushed rock {wrapped in t 3 II filter fabric) or Class 2 Penneable. (See specifications below) SPECIFICATIONS FOR CAL TRANS CLASS 2 PERMEABLE MATERIAL (68-1.025) SIEVE SIZE %PASSING I" ·•········•·• ................. 100 ¾" ····························· 90-100 ¾" ............................. 40-100 No. 4····························25-40 No. 8 ········· .. ···· ............. Jg.33 No. 30 ........................... 5-15 No. 50 ........................... 0-7 No. 200 ························· 0-3 Sand Equivalent> 75 1. Provide granular, non-expansive backfill in a 1: 1 gradient wedge behind the wall. Compact backfill to minimum 90% of laboratory standard. 2. 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. 3. Backdrain should consist of 4" diameter PVC pipe (Sch. 40 or equivalent) with perforations down. Drain to suitable outlet at a minimum 1 % fall. Provide ¾ " to ½ " crushed rock filter wrapped in filter fabric (Mirafi 140N or equivalent). Delete filter fabric if Caltrans Class 2 Permeable material is used. Compact Permeable Class 2 to minimum 90% of laboratory standard. 4. Seal back of wall with waterproofing in accordance with the architects specifications. 5. Provide positive drainage to disallow ponding of water above wall. A lined drainage ditch with a minimum 2% flow away from wall is recommended. • Use l ½ cubic foot per foot crushed rock with granular soil and 4 cubic foot per foot if expansive soil is present. VINJE & MIDDLETON ENGINEERING, INC. 2450 Auto Park Way Escondido, California 92029 760-743-1214 vinje.middleton@sbcglobal.net PLATE 7 V&M Job #19-119-F Setomber 20111 ATTACHMENT 1 Job #05-422-F and 05-423-F October 28. 2010 Kirk Patrick Development, LLC Attention: Mr. Ty Rossman P.O. Box 3811 Manhattan Beach. California 90266 SLOPE ST ABILITY, NEAR VERTICAL TEMPORARY CONSTRUCTION SLOPES, EXISTING CONTIGUOUS GRADED PADS LOCATED AT 475 PARK DRIVE AND 4488 ADAMS STREET, CARLSBAD, CALIFORNIA I. INTRODUCTION: Pad grading for the above referenced properties was observed by this office in 2005 and 2006. Upon completion, the following compaction reports were issued by this office: I. "As-Graded Compaction Report and Foundation Recommendations for Proposed Single-Family Residence Located at 475 Park Avenue, City of Carlsbad Drawing #423-8A, Project #CDP 03-12," Job #05-422-F, dated April 25, 2006. 2. "As-Graded Compaction Report and Foundation Recommendations for Proposed Single-Family Residence Located at 4488 Adams Street, City of Carlsbad Drawing#4 l 2-2A, Project #CDP 03-12," Job #05-423-F, dated April 25, 2006. Prior to site grading, the properties were studied for surface and subsurface conditions by this office which resulted in the following technical report: 1. "Preliminary Geotechnical Investigation, Undeveloped Hillside Lots, 4588 Adams Street, Carlsbad, California," Job #02-108-P, dated February 11, 2002. The above referenced compaction reports and preliminary investigation were reviewed and copies are on file with our office. We understand that the subject properties have sat idle and remain substantially unchanged since the issue of the compaction reports. The purpose of this letter is to address the temporary construction slopes at both properties which were constructed nearly 4½ years ago and remain. A site visit was conducted by the undersigned in connection with this effort on October 27, 2010. II. FINDINGS: Temporary construction slopes at both properties are largely in the IO feet high range, but do locally approach 12 feet high maximum. The slopes generally occur in near vertical conditions within the bottom 4 to 6-feet and Slope Stability Near Vertical Temporary Construction Slopes 475 Park Drive and 4488 Adams Street, Carlsbad Pagel October 28, 2010 range from approximately ¼: I to 1: I (horizontal to vertical) above. The construction slopes are in substantial conformance with our recommendations presented in the preliminary investigation (reference above) and were expected to be temporary slopes with wall and building construction to follow in a timely manner. Howevert we understand that the temporary construction slopes remain as constructed in 2006. The following was noted: 1. The temporary slopes are largely covered by jute matting. 2. The slopes expose cemented sandstone deposits. 3. Some minor erosion and shallow ruts are present on all temporary slopes. 4 More moderate erosion is present on the west end of the north temporary slope at the northern pad location ( 4 7 5 Park A venue). The noted erosion is the result from runoff in a brow ditch that drains over the slope and onto the building pad areas. Ill. CONCLUSIONS: The temporary construction slopes were expected to be only temporary. Howevert after remaining exposed for more than 4-years the slopes are considered to be performing well. Noted erosion of the slope faces is surficial. No evidence of deep-seated instability within the temporary slopes is indicated. The jute-matting should be maintained to impede further erosion of the slope faces, and consideration should be given to addressing the brow ditch that drains onto the north building pad. All the temporary slopes should be re-evaluated prior to building or wall constructions. Additional temporary slope recommendationst if warranted, can be given at that time. If you have any questions or need clarificationt please do not hesitate to contact the undersigned. Reference to our Job #05-422 and 423-F will help to expedite our response to your inquiries. We appreciate this opportunity to be of service to you. VINJE & MIDDLETON ENGINEERING, INC. Stev~8~&4L_ CEG #2362 SJM/mpr mprlmy files\grading department projects'OS-422 and 423-f-kirk patrick devclopmentlslope stability near vertical temp consuuction slopes letter ATTACHMENT 2 Job #05-423-F April 25, 2006 Kirk Patrick Development, LLC Attention: Mr. Ty Rossmann 936 Monterey Boulevard Hermosa Beach, California 90254 AS-GRADEDCOMPACTIONREPORT ANDFOUNDATIONRECOMMENDATIONSFOR PROPOSED SINGLE FAMILY RESIDENCE LOCATED AT 4488 ADAMS STREET, CITY OF CARLSBAD DRAWING #412-2A, PROJECT #CDP 03-12 In accordance with the Grading Ordinance for the City of Carlsbad, this as-graded compaction report has been prepared for the above referenced project. We have completed engineering observation and testing services in conjunction with the grading operations for the building pad and retaining driveway retaining wall backfills. This report summarizes the results of our tests and observations of the compacted fill. The compacted fill in the subject area was placed periodically from December 28, 2005 through April 11, 1006. Actual dates are shown on the enclosed compaction test result sheets. I. REFERENCES The following listed grading plan and document was used by this office as part of this project: A. Grading Plan prepared by Pasco Engineering. B. "Preliminary Geo technical Investigation" report, prepared by this office, dated February 11, 2002, Job #02-108-P. II. GRADING INFORMATION/GROUND PREPARATION Prior to grading operations, the site within the limits of the grading operations for the construction ofa building pad was cleared of vegetation. All questionable loose and compressible soils were also removed from the areas receiving fill. Adequate keys or benches were constructed a minimum of 2- feet into firm, undisturbed natural ground or formational soils prior to fill placement. The building area is a split level pad with a difference of JO-feet from the upper and lower levels. Both levels were undercut to an elevation of 58.0 to remove all loose and compressible soils. The final grades of the upper and lower pad was achieved by placing properly compacted fill. As-Graded Compaction Report 4488 Adams Street, Carlsbad Pagel April 25, 2006 Site preparation and grading were conducted in substantial conformance with Appendix Chapter 33, latest edition of the California Building Code, the Grading Ordinance for the City of Carlsbad and our above listed preliminary geotechnical report. All inspections and testing were conducted under the observation of this office. In our opinion, au embankments and excavations were constructed in substantial conformance with the provided grading plan, and are acceptable for their intended use. m. FILL PLACEMENT Fill was placed in 6 to 8-inch lifts and compacted by means of heavy construction equipment. Field density tests were performed in accordance with ASTM Method D-1556 sand cone method as the fill was placed. The moisture content for each density sample was also determined. The approximate locations of the field density tests are shown on the attached drawing. The locations of the tests were placed to provide the best possible coverage. Areas of low compaction, as indicated by the field density tests, were brought to the attention of the contractor. These areas were reworked by the contractor and retested. The test locations and final test results are summarized on the compaction test result table. Elevations and locations of field density tests were determined by hand level and pacing/tape measure relative to field staking done by others. The results of our field density tests and laboratory testing indicate that the fills at the site were compacted to at least 90% of the corresponding maximum dry density at the tested locations. If the building pad should undergo any prolonged seasonal wetting and drying periods prior to construction, remedial grading could be required depending on the site soil characteristics. Depths ofremoval and re-compact can best be determined just prior to construction by appropriate inspection and testing. IV. SITE CORROSION ASSESSMENT A site is considered to be corrosive to foundation elements, walls and drainage structures if one or more of the following conditions exists: • pH is less than 5.5. • Sulfate concentration is greater than or equal to 2000 ppm (0.2% by weight). • Chloride concentration is greater than or equal to 500 ppm (0.05% by weight). For structural elements, the minimum resistivity of soil (or water) indicates the relative quantity of soluble salts present in the soil (or water). In general, a minimum resistivity value for soil (or water) less than I 000 ohm-cm indicates the presence of high quantities of soluble salts and a higher propensity for corrosion. As-Graded Compaction Report 4488 Adams Street, Carlsbad V. APPROPRIATE LADORA TORY TESTS Page3 April 25, 2006 A. Maximum Dry Density Optimum Moisture Tests: The maximum dry density and optimum moisture contents of the different soil types used as compacted fill were determined in accordance with ASTM Method D-1557. 8. Expansion Tests: Expansion tests were conducted per 2001 UBC Standard Procedure 18-2 on representative samples of the on site soils during the preliminary investigative phase of the project in order to determine the expansion potential and to provide appropriate foundation recommendations. As no new soils were encountered during the grading operations, no additional testing was conducted. C. Direct Shear Tests: Direct shear tests were conducted on representative samples of the on site soils during the preliminary investigative phase of the project in order to determine the allowable bearing capacity and to provide retaining wall design parameters. As no new soils were encountered during the grading operations, no additional testing was conducted. D. Corrosion Testing: pH-Resistivity and sulfate testing were determined in accordance with California Test Method 643 and 417 respectively on a representative sample of the finish grade soils in the building pad area in order to determine the corrosiveness of the soil. VI. RECOMMENDATIONS THIS REPORT SHOULD BE CONSIDERED AS A PART OF THE PROJECT FOUNDATION PLANS AND MUST BE PROVIDED TO THE PROJECT ARCHITECT/STRUCTURAL ENGINEER TO ENSURE THE FOLLOWING FOUNDATION RECOMMENDATIONS ARE INCLUDED IN THOSE PLANS** The following minimum foundation recommendations for very low expansive (Expansion Index less than 21) bearing soils, classified using the "Unified Soil Classification System" or "USCS" as SM, with minimal indicated fill differential depth from our "Preliminary Geotechnical Investigation" report should be adhered to, and incorporated into the foundation plans. Foundation plans and details may be submitted to our office for review, to insure conformance with our recommendations. Please note (**) items for revised recommendations since the issuance of our referenced preliminary geotechnical report. A. Foundations, Monolithic Pour System Conventional shallow foundations with stem walls and slab-on-grade floors, or slab-on- ground with turned-down footings. As-Graded Compaction Report 4488 Adams Street, Carlsbad Page4 April 25, 2006 1. Continuous strip stem wall foundations and turned-down footings should be a minimum of I 5-inches wide by I 8-inches deep one and two story structures respectively. Spread pad footings should be at least 24-inches square and 12-inches deep, for one and two story structures. Minimum depths are measured from the lowest adjacent ground surface, not including the sand under the slab. Exterior continuous foundations or turned-down footings should enclose the entire building perimeter, to include the garage entryway. 2. Continuous interior and exterior stem wall foundations should be reinforced with a minimum of four #4 reinforcing bars. Place two bars 3-inches below the top of the stem, and two bars 3-inches above the bottom of the footing. Turned-down footings should be reinforced with a minimum of two #4 bars top and two #4 bars at the bottom Reinforcement for spread pad footings should be designed by the project structural engineer. 3. Foundations where the surface of the ground slopes more than I-unit vertical in 10-units horizontal ( 10% slope), shall be level or shall be stepped so that both top and bottom of such foundation are level. Individual steps in continuous footings shall not exceed 18- inches in height and the slope of a series of such steps shall not exceed I-unit vertical to 2-units horizontal (50%) unless otherwise specified. The steps shall be detailed on the structural drawings. The local effects due to the discontinuity of the steps shall also be considered in the design of foundations as appropriate and applicable. 4. Open or backfilled trenches parallel with a footing shall not be below a plane having a downward slope of I unit vertical to 2 units horizontal ( 50%) from a line 9-inches above the bottom edge of the footing, and not closer than I 8-inches from the face of such footing. 5. Where pipes cross under footings, the footings shall be specially designed. Pipe sleeves shall be provided where pipes cross through footings or footing walls and sleeve clearances shall provide for possible footing settlement, but not less than I-inch all around the pipe. ** 6. All interior slabs should be a minimum of 4-inches in thickness reinforced with #3 reinforcing bars spaced 18-inches on center each way, placed midheight in the slab. Use 4-inches of clean sand (SE 30 or greater) beneath all slabs. A well performing moisture/vapor retardant (10-mil or greater) must be placed midheight in the sand. Joints in the moisture/vapor retardant should be overlapped a minimum of 12-inches. 7. Provide re-entrant ( :i:270° comers) reinforcement for all interior slabs as generally shown on the enclosed "Isolation Joints and Re-Entrant Comer Reinforcement" detail. Re- entrant comers will depend on slab geometry and/or interior column locations. As-Graded Compaction Report 4488 Adams Street, Carlsbad Page5 April 252 2006 8. Provide "soft-cut" contraction/control joints consisting of sawcuts spaced IO-feet on center maximum each way for all interior slabs. 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 when the compressive strength reaches 150 to 800 psi. The "soft-cut" must be a minimum of 1-inch in depth and must not exceed 1 ¼-inch in depth or the reinforcing may be damaged. 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. B. Corrosiveness 1. Laboratory test results indicate that the minimum resistivity is greater than 1000 ohm-cm suggesting the presence of low quantities of soluble salts. Test results show that the chloride concentration is less than 500 ppm, and the pH is greater than 5.5. Based on the results of the available corrosion analyses, the project site is considered non-corrosive. The project site is not located within 1000-feet of salt or brackish water. 2. Based upon the result of the sulfate test, the amount of water soluble sulfate (S04) was found to be 0.001 percent by weight which is considered negligible ccording to the California Building Code Table No. 19-A-4. Portland cement Type II may be used. C. Paving and Concrete Improvements Not Within The Public or Private Street Right of Way 1. Exterior flatwork adjacent to buildings must be a minimum of 4-inches in thickness reinforced with 6x6/1 Oxl 0 welded wire mesh carefully placed 2-inches below the top of the slab. Provide "tool joint" or "soft cut" contraction/control joints spaced 10-feet on center (not to exceed 12-feet maximum) each way within 24-hours of concrete pour. The construction procedures for sawcuts (if used) are described in Item #A-8 above. 2. Concrete driveways and parking areas should consist of5-inch thick concrete reinforced with #3 reinforcing bars spaced 18-inches on center each way placed 2-inches below the top of the slab. The concrete should be placed over 6-inches subgrade compacted to a minimum of90% of ASTM 1557-91. As-Graded Compaction Report 4488 Adams Street, Carlsbad Page6 April 25, 2006 Where longitudinal grades exceed 15%, provide a minimum of 8-inch wide by 8-inch deep shear anchors dug perpendicular to the driveway longitudinal profile into the approved subgrade at 25-foot interval maximum. Provide "tool joint" or "soft cut" contraction/control joints spaced 10-feet on center (not to exceed 12-feet maximum) each way within 24-hours of concrete pour. The construction procedures for sawcuts (if used) are described in Item #A-8 above. ** 3. Asphalt concrete (AC) driveways and parking areas should consist of 3-inches AC over 6-inches Caltrans Class 2 aggregate base compacted to a minimum of95% over 6-inches subgrade compacted to a minimum of90% of ASTM 1557-91. Where longitudinal grades exceed 10%, ½-inch asphalt should be added to the design asphalt thickness for each 2% increase in grade or portion thereof. 4. Sub and basegrade soils should not be allowed to dry out or become saturated prior to placement of concrete or asphalt. Subgrade and basegrade soils shall be tested for proper moisture and compaction levels just prior to placement of the improvements. 5. Proper drainage must be maintained at all times so that no water from any source is allowed to infiltrate the sub or basegrade soils, or deterioration of the improvements may occur. D. Inspections 1. If required by the governing agency, this office should be notified to inspect or test the following prior to foundation concrete pours: a) Inspect the plumbing trenches beneath slabs after the pipes are laid and prior to backfilling. b) Test the plumbing trenches beneath slabs for minimum compaction requirements prior to sand and moisture barrier placement. c) Inspect the bottom of the footing trenches for proper embedrnent into firm compacted or formational soils, and inspect for proper footing width prior to placement of reinforcing steel d) Inspect the footing reinforcement size and placement. Inspect the slabs for proper thickness, reinforcing placement and size, inspect the sand thickness and moisture barrier placement and thickness, after the initial footing embedment and width inspection, and prior to concrete pour. As-Graded Compaction Report 4488 Adams Street, Carlsbad E. Soil Design Parameters Page7 April 25, 2006 The following soil design parameters are based upon the soils used in the construction of the building pad: 1. Use a friction angle of 33 degrees. 2. Use a wet density of 129.8 pcf. 3. Use a coefficient of friction of0.39 for concrete on compacted soils. 4. Use an active pressure of 38 pcf equivalent fluid pressure for cantilever, unrestrained walls with level backfill surface. 5. Use a active pressure of 58 pcfequivalent fluid pressure for cantilever unrestrained walls with a 2:1 (horizontal to vertical) backfill. 6. Use an at rest pressure of 59 pcf equivalent fluid pressure for restrained walls. 7. Use a passive resistance of 44 7 pcf equivalent fluid pressure for level surface condition at the toe. 8. Use an allowable foundation pressure of2,000 psffor minimum 15-inch wide by 18-inch deep footings. 9 Use an allowable lateral bearing pressure of 200 psf per foot for all structures except retaining walls. Notes: 1. Use a minimum safety factor of 1.5 for wall overturning and sliding stability. Because large movements must take place before maximum passive resistance can be developed, a safety factor of 2.0 may be considered if sensitive structures or improvements are planned near or adjacent to the top of the wall. 2. When combining passive and frictional resistance, the passive component should be reduced by one-third. 3. The allowable soil bearing pressure provided herein was determined for footings having a minimum width of 15-inches and a minimum depth of 18-inches below the lowest adjacent ground surface. This value may be increased 20% for each additional foot of As-Graded Compaction Report 4488 Adams Street, Carlsbad Page8 April 25, 2006 depth, and 20% for each additional foot of width to a maximum of 3,500 pst: if needed. The allowable soil bearing pressure provided herein is for dead plus live loads and may be increased by one-third for wind and seismic loading. 4. The lateral bearing earth pressures may be increased by the amount of the designated value for each additional foot of depth to a maximum of 1,500 pounds per square foot. F. General Recommendations I. The minimum steel reinforcement provided herein is based on soil characteristics only, and is not intended to be in lieu of reinforcement necessary for structural considerations. 2. Recommendations for a swimming pooJ/spa are not within the scope of this report. Ifa swimming pooJ/spa and associated structures are to be constructed, this office should be contacted in order to provide site specific recommendations prior to beginning any excavations. 3. All retaining walls should be provided with a drain along the backside as generally shown on the enclosed "Retaining Wall Drain" detail. Specific drainage provisions behind retaining wall structures must be inspected by this office prior to backfilling the wall. All backfill soils must be compacted to a minimum of 90% of the corresponding maximum dry density, ASTM 1557-91. 4. All underground utility trenches beneath interior and exterior slabs 12-inches or more in depth shall be compacted by mechanical means 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 trench backfill. No flooding or jetting of the backfill is allowed. 5. The planting of large trees behind any retaining wall will adversely affect their performance and should be avoided. G. Seismic Coefficients ** The following site specific seismic parameters for the above referenced project were detennined in accordance with the latest edition of the California Building Code requirements. The following parameters are consistent with the indicated project seismic environment and may be utilized for project design work. As-Graded Compaction Report 4488 Adams Street, Carlsbad Site Soil Seismic Profile Seismic Zone Type Zone Factor So 4 0.4 Seismic Source Type B Seismic Response Coefficients Na Nv Ca Cv Ts 1.0 l.l 0.44 0.68 0.621 Page9 April 25, 2006 To 0.124 According to Chaoter 16. Division IV and v. latest edition of the California Building Code Liquefaction and seismically induced settlements will not be factors in the development of the proposed structures and improvements. H. Setbacks 1. Footings located on or adjacent to the top of slopes should be extended to a sufficient depth to provide a minimum horizontal distance of7-feet or one-third of the slope height, whichever is greater (need not exceed 40-feet maximum) between the bottom edge of the footing and face of slope. Reinforcement for deepened footings should be provided by the project structural engineer and detailed on the approved foundation plans. 2. The outer edge of all slopes experience "down slope creep", which may cause distress to structures. If any structures including buildings, patios, sidewalks, swimming pools, spas etc, are placed within the setback, FURTHER RECOMMEND A TIO NS WILL BE REQUIRED. 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 recommendations are believed to be reasonable and in keeping with the local standards of construction practice. Special attention should be given to any "re-entrant" comers (±270 degree comers) and curing practices during and after concrete pour in order to further minimize shrinkage cracks. I. Slopes 1. All slopes should be landscaped with types of plants and planting that do not require excessive irrigation. Excess watering of slopes should be avoided. Slopes left unplanted will be subject to erosion. The irrigation system should be installed in accordance with the governing agencies. 2. Water should not be allowed to flow over the slopes in an uncontrolled manner. Until landscaping is fully established, plastic sheeting should be kept accessible to protect the As-Graded Compaction Report 4488 Adams Street, Carlsbad Page 10 April 25, 2006 along the top edges of all fill slopes. In no case should water be allowed to pond or flow over slopes. 3. Brow ditches should be constructed along the top of all cut slopes sufficient to guide runoff away from the building site and adjacent fill slopes prior to the project being completed. J. Drainage 1. The owner/developer is responsible to insure adequate measures are taken to properly finish grade the building pad after the structures and other improvements are in place so that the drainage waters from the improved site and adjacent properties are directed away from proposed structures in accordance with the designed drainage patterns shown on the approved plans. 2. A minimum of 2% gradient should be maintained away from all foundations. Roof gutters and downspouts should be installed on the building, all discharge from downspouts should be led away from the foundations and slab to a suitable location. Installation of area drains in the yards should also be considered. 3. Planter areas adjacent to foundations should be provided with damp/water proofing, using an impermeable liner against the footings, and a subdrainage system within the planter area. 4. It should be noted that shaUow groundwater conditions may still develop in areas where no such conditions existed prior to site development. This can be contributed to by substantial increases of surface water infiltration resulting from landscape irrigation which was not present before the development of the site. It is almost impossible to absolutely prevent the possibility of sbaUow groundwater on the entire site. Therefore, we recommend that shaUow groundwater conditions be remedied if and when they develop. 5. The property owner should be made aware that altering drainage patterns, landscaping, the addition of patios, planters, and other improvements, as well as over irrigation and variations in seasonal rainfall, all affect subsurface moisture conditions, which in turn affect structural performance. VD. GENERAL INFORMATION It should be noted that the characteristics of as-compacted fill may change due to post-construction changes from cycles of drying and wetting, water infiltration, applied loads, environmental changes, As-Graded Compaction Report 4488 Adams Street, Carlsbad Page 11 April 25, 2006 etc. These changes can cause detrimental changes in the fill characteristics such as in strength behavior, compressibility behavior, volume change behavior, permeability, etc. Where present, clayey deposits are subjected to continued swelling and shrinkage upon wetting and drying. Maintaining a uniform moisture during the post construction periods is essential in the future performance of the site structures and improvements. 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 nonnal concrete shrinkage during the curing process. The features depend chiefly upon the condition of concrete and weather conditions at the tome of construction and do not reflect detrimental ground movement. Hairline stucco cracks will often develop at windows/door comers, and floor surface cracks up to 1/e-inch wide in 20 lineal feet may develop as a result ofnonnal concrete shrinkage ( according to the American Concrete Institute). The amount of shrinkage related cracks that occur in concrete slab-on-grades, flatwork 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 nonnal 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: A. Use the stiffest mix that can be handled and consolidated satisfactorily. B. Use the largest maximum size of aggregate that is practical, for example concrete made with %-inch maximum size aggregate usually requires about 40-pounds (nearly 5 gallons) more water per cubic yard than concrete with 1-inch aggregate. C. 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. This office is to be notified no later than 2 p.m. on the day before any of the following operations begin to schedule appropriate testing and/or inspections. A. Fill placed under any conditions 12-inches or more in depth, to include: l. Building pads. 2. Street improvements, sidewalks, curbs and gutters. AsRGraded Compaction Report 4488 Adams Street, Carlsbad 3. Utility trench backfills. 4. Retaining wall backfills. Page 12 April 25, 2006 5. The spreading or placement of soil obtained from any excavation (spoils from footings, underground utilities, swimming pools, etc.). B. Inspection and testing of subgrade and basegrade beneath driveways, patios, sidewalks, etc., prior to placement of pavement or concrete. C. Moisture testing. D. Geotechnical foundation inspections, if required by the governing agency. E. Any operation not included herein which requires our testing, observation, or inspection for certification to the appropriate agencies. VIII. LIMIT A TIO NS Our description of grading operations, as well as observations and testing services herein, have been limited to those grading operations performed periodically from December 28, 2005 through April 11, 1006. The conclusions contained herein have been based upon our observations and testing as noted. No representations are made as to the quality or extent of materials not observed and tested. This report is issued with the understanding that the owner or his representative is responsible to ensure 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 soil 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 soils 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. The attached drawing details the approximate locations of cuts, fills, and approximate locations of the density tests taken, and is applicable to the site at the time this report was prepared. This report should be considered valid for permit purposes for a period of six months and is subject to review by our firm following that time. IF ANY CHANGES ARE MADE, PAD SIZE, BUILDING As-Graded Compaction Report 4488 Adams Street. Carlsbad Page 13 April 25. 2006 should be considered valid for permit purposes for a period of six months and is subject to review by our firm following that time. IF ANY CHANGES ARE MADE, PAD SIZE, BUILDING LOCATION, ELEV A TIO NS, ETC., THIS REPORT WILL BECOME INVALID AND FURTHER ENGINEERING AND RECOMMENDATIONS WILL BECOME NECESSARY. If you have any questions or need clarification. please contact this office at your convenience. Reference to our Job #05-423-F will help to expedite our response to your inquiries. We appreciate this opportunity to be of service to you. VINJE & MIDDLETON ENGINEERING, INC. Ralph M. Vinje GE #863 SMSS/mpr Distribution: Addressee: (6) mpr\my lilcs\lill control rcports\05-423-fkirk patrick dc,clopmcnl 4488 ndnms str~-ct as-grade n.:pon JOB NO: 05-423-F NAME: Kirk Patrick Development, LLC LOCATION: 4488 Adams Street, Carlsbad TEST RESULTS Maximum Dry Density/Optimum Moisture Content, ASTM 1557: Soil Type 3: Red Brown Fine to Medium Sand (Fill/Terrace Deposit)** Maximum Dry Density: 131.4 pcf Optimum Moisture: I 0.3% Field Density Test Results: Residential Pad and Retaining Wall Backfills EL or Ht. Of Date Test Fill In 200X No. Location Ft. 12/28 I Easterly Driveway Wall +2.0 12/28 2 Easterly Driveway Wall +4.0 12/29 3 Lower Level, Pad 60.0 12/29 4 Lower Level, Pad 62.0 2006 01/04 5 Upper Level, Pad 64.0 01/04 6 Upper Level, Pad 94.0 01/06 7 Upper Level, Pad 66.0 01/06 8 Upper Level, Pad 68.0 01/09 9 Upper Level, Pad 70.0 01/09 10 Upper Level, Pad 70.0 01/09 II Upper Level, Pad 71.5 04/11 12 Southwesterly Driveway Wall +2.0 04/11 13 Southwesterlv Drivewav Wall +2.0 % Field Moisture I 1.5 12.2 10.8 12.0 13.4 12.8 11.7 11.2 13.5 13.0 10.9 I 1.3 12.4 .. From our "Preliminary Geotechnical Investigation" report, dated February 11, 2002, Job #02-108-P mprlmy files\fill control reports\05-422-fkirk patrck development 4488 ada~ street densily lest results Field Mn Dry Dry % Density Density Relative Pcf Pcf Comp. Comment 119.2 131.4 90.7 121.4 131.4 92.4 Finish Grade 120.3 131.4 91.6 Bottom of Removal at El. 58.0 118.9 131.4 90.5 115.6 131.4 88.0 Test Failed 118.5 131.4 90.2 Retest #5 120.1 131.4 91.4 119.4 131.4 90.9 116.0 131.4 88.3 Test Failed 118.7 131.4 90.3 Retest #9 120.6 131.4 91.8 Finish Grade 119.7 131.4 91.1 Finish Grade 118.8 131.4 90.4 Finish Grade Job #05-423-F Job Name: Kirk Patrick Development, LLC Location: 4488 Adams Street, Carlsbad RESULTS OF LADORA TORY TESTING pH and Resistivity Test: A pH/pH and resistivity tests was performed on a representative sample of the near finish soils used in the grading of the building pad using" Method for Estimating the Service Life of Steel Culverts," in accordance with California Test Method CTM 643. The result is presented below. Samole Location Minimum Resistivitv (OHM-CM'I pH Near Finish Grade 1120 6.76 Years to Perforation of Steel Culverts Sample Location Ga2e 18 16 14 12 10 8 Near Finish Grade Years to Perforation 14 18 22 30 39 47 Sulfate Test: A sulfate test was performed on a representative sample of the near finish grade soils used in the grading of the building pad in accordance with California Test Method CTM 417. The result is presented below. Sample Location Near Finish Grade Amount of Water Soluble Sulfate (SO4) In Soil (% bv WeiPht) 0.001 mpr\my filcs\fill conlrol rcports'il5-423•fkirk patrick developmcnl 4488 adams stn:ct lab test results Waterproofing ' RETAINING WALL DRAIN DETAIL Typical -no scale ompetent, approved· soils or bedrock .... .,. CONSTRUCTION SPECIFICATIONS: 1. Provide granular, non-expansive backfill soil in 1: 1 gradient wedge behind wall. Compact backfill to minim um 90% of laboratory standard. 2. 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. 3. Backdrain should consist of 4" diameter PVC pipe (Schedule 40 or equivalent) with perforations down. Drain to suitable outlet at minimum 1%. Provide¾" -1½" 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. 4. Seal back of wall with waterproofing In accordance with architect's specifications. 5. Provide positive drainage to disallow ponding of water above wall. Lined drainage ditch to minimum 2% flow away from wall is recommended. * Use 1 ½ cubic foot per foot with granular backfill soil and 4 cubic foot per foot if expansive backfill soil is used, VINJE & MIDDLETON ENGINEERING, INC. PLATEl1 NOTES: ISOLATION JOINTS AND RE-ENTRANT CORNER REINFORCEMENT Typical -no scale (a) {b) ISOLATION JOINTS RE-ENTRANT CORNER -- REINFORCEMENT NO. 4 BARS PLACED 1.51 ' BELOW TOP OF SLAB (c) ---RE-ENTRANT CORNER CRACK 1. Isolation joints around the columns should be either circular as shown in (a) or diamond shaped as shown in (b). Jf no isolation joints are used around columns, or if the comers of the isolation joints do not meet the contraction joints, radial cracking as shown in (c)may occur (reference ACI). 2. In order to control cracking at the re-entrant comers (±270" comers), provide reinforcement as shown in (c). 3. Re-entrant comer 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 engineeririg and construction factors. VINJE & MIDDLETON ENGINEERING, INC. PLATEl2 I .., ., .. .., ~. (!)DRIVEWAYS~~ (I) BACKYARD SECTION •r••~ &_'"aTH H~· ~7~ T" . . lll"&J. ...... .. --· ED BROW DITCH DBTAIL A~~ PARCEL MAP10 . ' ~1·-, -:[.:..r:: .. 206-192-.37 PARCEL2 MAP10175 ~LN' #DlfCEM'I PlSJN mart&Je_/ ED CROSS SECflON E _,....., , ' _,,/ '\, ---·· ----' l...>. , ~t ------· ID / '\_ ,-;.:,. . if '\~' -·--·--· 6:,/,' ~--~~-,_<;;, 175 '\ ,,/ /,,-• ' /_/ &,.• ,,._ 'v_:>,fJ:-'' /// ®CH-------:=~ , ,,.:,,~'l .,,., \~ lll'fnlllt.lU , ,~~/' / /'.',~<-" ~· :J,;-, /./ -~x// ' ABB NS EASEMENTS / ~/ ·" ;<ft I ·-1/,/ ,,/' !ill crg.g;em lw •..WmnllM.PUana. 1/:,/ ~SOI Cl<JO,lllohel, Adams SL SFR ................. ~c.- ATTACHMENT 3 ti 19-119-F 4488 Adams Street, Carlsbad Latitude, Longitude: 33.1473, -117.3260 <,_, % <?. ~ Agua Hedionda Lagoon q i i \ ..,. 9-. 0 ~ "a ~ \ t ~ \ ~ \ \ \ ' ' \ \ ' ' ' -~ ' ----\ Go · gle Data ~ark Dr Design Code Reference Document Risk category 3/22/2019, 11:33:02 AM ASCE7-10 Ill Sita Cla1111 Type Value Ss 1.13 S1 0.434 5Ms 1.184 SM1 0.679 5os 0.769 S01 0.453 Type Value soc D Fa 1.046 Fv 1.566 PGA 0.446 FpGA 1.054 PG~ 0.47 TL 8 SsRT 1.13 SsUH 1.192 SsD 1.504 S1RT 0.434 S1UH 0.434 S10 0.603 PGAd 0.563 CRs 0.947 CR1 0.999 Description MCER gmund motion. (for 0.2 second period) MCER ground motion. (for 1.0s period) Site-modified spectral acceleration value Site-modified spectre! ecceleratlon value Numeric seismic design value at 02 second SA Numeric seismic design value at 1.0 second SA Description Seismic design category Site ampllflcatlon fader al 0.2 second Site amp6ficatlon factor at 1.0 second MCEa peak ground acceleration Site amplification factor at PGA Site modlfled peak ground acceleration Longi)eriod transition period in seconds Probabllistlc risk-targeted ground motion. (0.2 second) 0-Stlff Soil Factored uniform-hazard (2% probebmty of exceedance In 50 years) spectral acceleration Factored detenninislic acceleration vak.le. (0.2 second) Probabilistic risk-targeted ground motion. (1.0 second) Feclored uniform-hazard (2% probability of exceedance In 50 years) spectral ecceleretlon. Factored deterministic acceleration value. (1.0 second) Factored determlnlstlc acceleration vak.le. (Peak Ground Acceleration) Mapped value of the risk coefficient at short periods Mapped value of the risk coefficient at e period of 1 s z ,.. 1Z. :;· "' -$' OS HPD Map data ©2019 Google :§ en Cl) MCER Response Spectrum 1.5 1.0 0.5 0.0 0.0 2.S 5.0 Period, T (sec) -sa(g) 0.8 0.6 0.4 0.2 0.0 Design Response Spectrum 0.0 2.5 5.0 Period, T (sec) -Sa(g) 7.5 7.5 DISCLAIMER Whila the infonnetlon presented on this website Is believed to be correct, SE.~Q£ /.Qfil-iPD. end its sponsors and contributors assume no responsibility or liability for its accuracy. The material presented In this web application should not be used or relied upon for any specific appficalion without competent examination and verification of Its accuracy, suilability and applicability by engineers or other licensed professionals. SEAOC / OSHPD do not intend that the use of this lnrormauon replace the sound judgment of such competent professionals, having experience and knowledge In the field of practice, nor to substitute for the standard of care required of such professionals In interpreling and applying Iha results of the seismic data provided by this website. Users of the lnfonnalion from this website assume all liabi~ty arising Imm such use. Use of the output of this website does not imply approval by Iha governing building code bodies responsible for building code approval and Interpretation for the building site described by latitudenongitude location in the search results of thls webstle. Appendix B OS HPD 21-259-F 4588 Adams Street, Carlsbad 21-259-P Latitude, Longitude: 33.1473, -117.3260 Date Design Code Reference Document Risk Category Site Class fype Value S5 1.049 S1 0.38 SMs 1.134 Sr.41 null -See Section 11.4.8 Sos 0.756 S01 null -See Section 11.4 .8 Type Value soc null -See Section 11.4.B Fa 1.08 Fy null -See Section 11.4.B PGA 0.462 FPGA 1.138 PGAM 0.526 TL 8 SsRT 1.049 SsUH 1.173 SsD 1.5 S1RT 0.38 S1UH 0.42 510 0.6 PGAd 0.538 CRs 0.895 CR1 0.906 E & L Pure Air\t Description 10/9/2021, 10:09:57 PM ASCE7-16 II O-Stilf Soll MCER ground motion. (for 0.2 second period) Description MCER ground motion. (for 1.0s period) Site-modified spectral acceleration value Slte-modilied spectral acceleration value Numeric seismic design value at 0.2 second SA Numeric seismic design value at 1.0 second SA Seismic design category Site amplification factor al 0.2 second Site amplification factor al 1.0 second MCEG peak ground acceleration Site amplification factor at PGA Sile modified peak ground acceleration Long-period transition period in seconds Probablllstlc risk-targeted ground motion. (0.2 second) Factored uniform-hazard (2% probability of exceedance In 50 years) spectral acceleration Factored deterministic acceleration value, (0,2 second) Probabilistic risk-targeted ground motion. (1.0 second) Factored uniform-hazard (2% probability of exceedance In 50 years) spectral acceleration. Factored deterministic acceleration value. (1.0 second) Factored deterministic acceleration value. (Peak Ground Acceleration) Mapped value of the risk coefficient at short periods Mapped value of the risk coefficient at a period of 1 s Map data <02021 Appendix C HETHERINGTON ENGINEERING, INC. SOIL & FOUNDATION ENGINEERING • ENGINEERING GEOLOGY• HYDROGEOLOGY City of Carlsbad Community and Economic Development 1635 Faraday Avenue Carlsbad, California 92008-7314 Attention: Ms. Amy Wickerham September 16, 2021 Project No. 9490.1 Log No. 21608 Subject: THIRD-PARTY GEOTECHNICAL REVIEW (FIRST) 4588 Adams Street Carlsbad, California GR202 l-0032/CD02-24 References: I) "Preliminary Geotechnical Investigation, Undeveloped Hillside Lots, 4588 Adams Street, Carlsbad, California," by Vinje & Middleton Engineering, Inc., dated February 11, 2002. 2) "Grading Plans For: Adams St. SFR, 4588 Adams Street, Carlsbad, CA 92008 by La Costa Engineering, dated June 23, 2021 (4-Sheets). 3) "Slope Stability, Near Vertical Temporary Construction Slopes, Existing Contiguous Graded Pads Located at 4575 Park Drive and 4588 Adams Street, Carlsbad, California," by Vinje and Middleton Engineering, Inc., dated October 28, 20 I 0. Dear Ms. Wickerham: In accordance with your request, Hetherington Engineering, Inc. has provided third-party geotechnical review of Reference I. The following comments are provided for analyses and/or response by the Geotechnical Consultant. 1. Due to the age of the report, the Consultant should update Reference 1 to comply with requirements of the 2019 California Building Code, ASCE 7-16, and City of Carlsbad requirements. 2. The Consultant should review the project grading plan (Reference 2) and foundation plans, provide any additional geotechnical analyses/recommendations considered necessary, and confirm that the plans have been prepared in accordance with the geotechnical recommendations. 5365 Avenida Encinas, Suite A• Carlsbad, CA 92008-4369 • (760) 931-1917 • Fax (760) 931-0545 333 Third Stree • L~guna Beach, CA 9265 • (949) 715-5440 • Fax (949) 715-5442 www.hetheringtonengineering.com THIRD-PARTY GEOTECHNICAL REVIEW (FIRST) Project No 9490.1 Log No. 21608 September 16, 2021 Page 2 3. The Consultant should provide an updated geotechnical map utilizing the current grading plan for the project to clearly show (at minimum): a) existing site topography, b) proposed structures/improvements, c) proposed finished grades, d) geologic conditions, e) locations of the subsurface exploration, f) temporary construction slopes, g) remedial grading, etc. 4. The Consultant should provide geologic cross-sections utilizing the current grading plan to clearly show (at minimum) a) existing site topography, b) proposed structures/improvements, c) proposed finished grades, d) geologic contacts, e) geologic structure, f) locations of the subsurface explorations, g) temporary construction slopes,, and h) remedial grading, etc. 5. The Consultant should provide a detailed description of proposed site grading, structures/improvements, foundation type, etc. 6. The Consultant should discuss regional geologic condition, geologic structure, and faulting. 7. The Consultant should address the site tsunami potential. 8. The Consultant should address impacts to adjacent property and improvements as a result of site grading and construction. 9. The Consultant should provide a description of what are considered approved foundation embedment materials. I 0. The Consultant should address expected total and differential settlement due to grading and foundation loads. 11. The Consultant should specify the sulfate exposure category (AC! 318) based on soluble sulfate testing and provide recommendations for sulfate resistant concrete, if necessary, or default to a severe exposure category, if testing is not available. 12. The Consultant should provide a list of codes, published maps/reports used in the preparation of the report. Please call if there are any questions. HETHERINGTON ENGINEERING, INC. THIRD-PARTY GEOTECHNICAL REVIEW (FIRST) Project No 9490. I Log No. 21608 September 16, 2021 Page 3 Sincerely, HETHERINGTON ENGINEERING, INC. Paul A. Bogseth Professional Geologist ~;~,jo~F.1~\"~~J'.~-::::. Certified Engineeri Ge og · s( I Certified Hydrogeologist 591 (expires 3/31/22) gineer 30488 otechnical Engineer 397 (expires 3/31/22) Distribution: I-via e-mail (Amy.Wickerham@carlsbadca.gov) 1-via e-mail (Tim.Carroll(@.carlsbadca.gov) HETHERINGTON ENGINEERING, INC. September 16, 2021 Project No. 9490.1 Log No. 21608 City of Carlsbad Community and Economic Development 1635 Faraday Avenue Carlsbad, California 92008-7314 Attention: Ms. Amy Wickerham Subject: THIRD-PARTY GEOTECHNICAL REVIEW (FIRST) 4588 Adams Street Carlsbad, California GR2021-0032/CD02-24 References: 1) “Preliminary Geotechnical Investigation, Undeveloped Hillside Lots, 4588 Adams Street, Carlsbad, California,” by Vinje & Middleton Engineering, Inc., dated February 11, 2002. 2) “Grading Plans For: Adams St. SFR, 4588 Adams Street, Carlsbad, CA 92008 by La Costa Engineering, dated June 23, 2021 (4-Sheets). 3) “Slope Stability, Near Vertical Temporary Construction Slopes, Existing Contiguous Graded Pads Located at 4575 Park Drive and 4588 Adams Street, Carlsbad, California,” by Vinje and Middleton Engineering, Inc., dated October 28, 2010. Dear Ms. Wickerham: In accordance with your request, Hetherington Engineering, Inc. has provided third-party geotechnical review of Reference 1. The following comments are provided for analyses and/or response by the Geotechnical Consultant. 1. Due to the age of the report, the Consultant should update Reference 1 to comply with requirements of the 2019 California Building Code, ASCE 7-16, and City of Carlsbad requirements. 2. The Consultant should review the project grading plan (Reference 2) and foundation plans, provide any additional geotechnical analyses/recommendations considered necessary, and confirm that the plans have been prepared in accordance with the geotechnical recommendations. SOIL & FOUNDATION ENGINEERING ENGINEERING GEOLOGY HYDROGEOLOGY (760) 931-1917 Fax (760) 931-0545 333 Third Stree Laguna Beach, CA 9265 (949) 715-5440 Fax (949) 715-5442 Carlsbad, CA 92008-43695365 Avenida Encinas, Suite A HETHERINGTON ENGINEERING, INC. www.hetheringtonengineering.com THIRD-PARTY GEOTECHNICAL REVIEW (FIRST) Project No 9490.1 Log No. 21608 September 16, 2021 Page 2 3. The Consultant should provide an updated geotechnical map utilizing the current grading plan for the project to clearly show (at minimum): a) existing site topography, b) proposed structures/improvements, c) proposed finished grades, d) geologic conditions, e) locations of the subsurface exploration, f) temporary construction slopes, g) remedial grading, etc. 4. The Consultant should provide geologic cross-sections utilizing the current grading plan to clearly show (at minimum) a) existing site topography, b) proposed structures/improvements, c) proposed finished grades, d) geologic contacts, e) geologic structure, f) locations of the subsurface explorations, g) temporary construction slopes,, and h) remedial grading, etc. 5. The Consultant should provide a detailed description of proposed site grading, structures/improvements, foundation type, etc. 6. The Consultant should discuss regional geologic condition, geologic structure, and faulting. 7. The Consultant should address the site tsunami potential. 8. The Consultant should address impacts to adjacent property and improvements as a result of site grading and construction. 9. The Consultant should provide a description of what are considered approved foundation embedment materials. 10. The Consultant should address expected total and differential settlement due to grading and foundation loads. 11. The Consultant should specify the sulfate exposure category (ACI 318) based on soluble sulfate testing and provide recommendations for sulfate resistant concrete, if necessary, or default to a severe exposure category, if testing is not available. 12. The Consultant should provide a list of codes, published maps/reports used in the preparation of the report. Please call if there are any questions. HETHERINGTON ENGINEERING, INC. THIRD-PARTY GEOTECHNICAL REVIEW (FIRST) Project No 9490.1 Log No. 21608 September 16, 2021 Page 3 Sincerely, HETHERINGTON ENGINEERING, INC. Paul A. Bogseth Mark D. Hetherington Professional Geologist 3772 Civil Engineer 30488 Certified Engineering Geologist 1153 Geotechnical Engineer 397 Certified Hydrogeologist 591 (expires 3/31/22) (expires 3/31/22) Distribution: 1-via e-mail (Amy.Wickerham@carlsbadca.gov) 1-via e-mail (Tim.Carroll@carlsbadca.gov) HETHERINGTON ENGINEERING, INC. November 17, 2021 Project No. 9490.1 Log No. 21678 City of Carlsbad Land Development & Engineering 1635 Faraday Avenue Carlsbad, California 92008-7314 Attention: Mr. David Rick Subject: THIRD-PARTY GEOTECHNICAL REVIEW (SECOND) 4588 Adams Street Carlsbad, California GR2021-0032/CD02-24 References: Attached Dear Mr. Rick: In accordance with your request, Hetherington Engineering, Inc. has provided third-party geotechnical review of References 5, 5a, and 5b. The site was graded in 2005-2006 for the same grading configuration as depicted on the current grading plan (Reference 2). The Consultant has provided recommendations to prepare the site for construction, and foundation recommendations. Based on our review, the Geotechnical Consultant has responded to our prior comments and we have no additional comments. Observation and testing by the Geotechnical Consultant during grading and construction should be required to verify anticipated conditions or to revise the geotechnical recommendation as considered necessary. A final geotechnical report of grading and construction should be required. Sincerely, HETHERINGTON ENGINEERING, INC. Paul A. Bogseth Mark D. Hetherington Professional Geologist 3772 Civil Engineer 30488 Certified Engineering Geologist 1153 Geotechnical Engineer 397 Certified Hydrogeologist 591 (expires 3/31/22) (expires 3/31/22) Distribution: 1-via e-mail (David.Rick@carlsbadca.gov) 1-via e-mail (Tim.Carroll@carlsbadca.gov) 1-via e-mail (ldetracking@carlsbadca.gov) SOIL & FOUNDATION ENGINEERING ENGINEERING GEOLOGY HYDROGEOLOGY (760) 931-1917 Fax (760) 931-0545 333 Third Street Laguna Beach, CA 92651 (949) 715-5440 Fax (949) 715-5442 Carlsbad, CA 92008-43695365 Avenida Encinas, Suite A HETHERINGTON ENGINEERING, INC. www.hetheringtonengineering.com REFERENCES 1. “Preliminary Geotechnical Investigation, Undeveloped Hillside Lots, 4588 Adams Street, Carlsbad, California”, by Vinje & Middleton Engineering, Inc., dated February 11, 2002. 2. “Grading Plans For: Adams St. SFR, 4588 Adams Street, Carlsbad, CA 92008 by La Costa Engineering, dated June 23, 2021 (4-Sheets). 3. Grading Plans For: Adams St. SFR, 4588 Adams Street, Carlsbad, CA 92008 by La Costa Engineering, dated June 23, 2021 (4-Sheets). 4. “Third-Party Geotechnical Review (First), 4588 Adams Street, Carlsbad, California”, by Hetherington Engineering, Inc., dated September 16, 2021. 5. “Update Compaction Report & Response to Third Party Review, Graded Residential Pad, 4588 Adams Street, Carlsbad, California, (APN 206-792-38)”, by Vinje & Middleton Engineering, Inc., dated October 18, 2021. 5a. “Updated Compaction Report, Graded Pad, 4488 Adams Street, Carlsbad, California”, by Vinje & Middleton Engineering, Inc., dated March 29, 2019. 5b. “As-Graded Compaction Report and Foundation Recommendations for Proposed Single Family Residence Located at 4488 Adams Street, City of Carlsbad, Drawing #412-2A, Project #CDP 03-12”, by Vinje & Middleton Engineering, Inc., dated April 25, 2016. HETHERINGTON ENGINEERING, INC.