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HomeMy WebLinkAboutCDP 2020-0024; TOYOTA CARLSBAD; GEOTECHNICAL RESPONSES TO COMMENTS; 2023-09-14September 14, 2023 Toyota Carlsbad Universal Engineering Sciences (UES) 1441 Montiel Road, Suite 115 Escondido, CA 92026 p. 760.746.4955 I TeamUES.com UES/CTE Job No. 10-15029G 5424 Paseo Del Norte Carlsbad, California 92008 Attention: Subject: Reference: Mr. Kevin Carroll (760) 496-2931 kcarroll@lexuscarlsbad.com Response to Second Round of Third Party Geotechnical Review Proposed Sales Building at Toyota Carlsbad 5434 Paseo Del Norte, Carlsbad, California 92008 Ninyo & Moore Project No . 109343017, Dated August 1, 2023 End of Document (Appendix A) Dear Mr. Carroll As requested, Universal Engineering Sciences (UES/CTE) provides the following response to the Second Round of Third Party Geotechnical Review by Ninyo & Moore dated August 1, 2023. The responses provided below are numbered based on the Comment Numbers. A copy of the Second Round of Third Party Geotechnical Review is provided as Appendix B. Comment Issue No. 7 through 12 were not formally addressed in the CTE Letter dated June 19, 2023. Accordingly, the following comments remain: Comment Issue No. 7: The referenced geotechnical reports (CTE, 2019; 2021b) references the County of San Diego BMP Design Manual (2016). The Geotechnical Consultant should review the City of Carlsbad BMP Design Manual (2023) and provide updated recommendations and/or worksheets based on the City of Carlsbad BMP Design Manual (2023). Response: CTE/UES has provided the Geotechnical Engineer Analysis per the City of Carlsbad BMP Design Manual (2023) and is provided in Appendix C. Comment Issue No. 8: The Geotechnical Consultant should provide a statement regarding the impact of the proposed grading and construction on adjacent properties and improvements. Response: CTE/UES does not anticipate adverse impact from grading on adjacent properties, provided our previously provided geotechnical recommendations are implemented. Remedial excavations should extend laterally at least five feet beyond the limits of the proposed improvements, where feasible. If overexcavations encroach upon property lines or adjacent structures the temporary excavation should Environmental Consulting I Geotechnical Engineering I Materials Testing & Inspections Occupational Health & Safety I Building Sciences & Code Compliance I Virtual Design Consulting flUES~ Response to Second Round of Third Party Geotechnical Review Sales Building at Toyota Carlsbad Project No. 10-150296 Page 2 generally be sloped at a 1:1 (horizontal to vertical) down to the prescribed overexcavation depth. Depending upon proximity and condition of exposed soils, overexcavation in slot cuts may be recommended by the geotechnical engineer. Comment Issue No. 9: The project plans (Universal Engineering Services, 2023) show permeable pavers adjacent to the existing and proposed structures. The Geotechnical Consultant should comment on the suitability of the infiltration elements being adjacent to these structures and to provide recommendations for setbacks or mitigation measures, as appropriate. Additionally, the Geotechnical Consultant should also provide pervious pavement recommendations. Response: Actual paver dimensions were not provided; therefore, actual paver pavement sections may require modification. The following Table provides preliminary pervious paver pavement sections. However, these recommendations are not intended to supersede more stringent or manufacturer's requirements. It appears permeable pavers are sloped away from structures; therefore, we don't anticipate impacts to structures. It is acceptable from a geotechnical perspective to place an impermeable liner beneath pervious paver areas that are within ten feet of a structure, with the edge of the liner nearest the structure turned up and extending to the finished paver grade to act as a barrier to infiltrate migrating towards the structure. If aggregate base or other import material is used beneath the pervious pavers it should consist of non- recycled or Class 2 permeable material with less than 10% fines (materials passing the #200 sieve). RECOMMENDED PAVEMENT THICKNESSES Design Minimum Caltrans Traffic Area Assumed Subgrade Paver Class 2 Traffic "R"-Value Thickness Permeable Index (inches) Materials Parking or Light to 5.5 55+ 2.5 4.0 Moderate Drive Areas Comment Issue No. 10: The project plans (Universal Engineering Services, 2023) indicate the proposed improvements will span across fill and cut material of the old paralic deposits. The geotechnical Consultant should provide recommendations for cut/fill transition. Response: The following was provided in Appendix D of the referenced report dated January 19 2021: All lot pad areas, including side yard terraces, that span cut/fill transitions, should be overexcavated to a minimum depth of 3 feet and replaced with a uniform layer of compacted fill. Actual depth of overexcavation may vary and should be delineated by the geotechnical consultant during grading, especially where deep or drastic transitions are present. Additionally, the minimum fill depth beneath and individual building pad should not be less than one-third the maximum fill depth beneath the same building pad. 1441 Montiel Road, Suite 115, Escondido, CA 92026 p. 760.746.4955 I oneues.com flUES~ Response to Second Round of Third Party Geotechnical Review Sales Building at Toyota Carlsbad Project No. 10-150296 Page 3 For pad areas created above cut or natural slopes, positive drainage should be established away from the top-of-slope. This may be accomplished utilizing a berm drainage swale and/or an appropriate pad gradient. A gradient in soil areas away from the top-of-slopes of 2 percent or greater is recommended. Comment Issue No. 11: The project plans (Universal Engineering Services, 2023) indicate the existing structure will be demolished prior to construction of the new improvements. The Geotechnical Consultant should note any impacts to the recommendations for the new improvements. Response: CTE/UES does not anticipate any impact due to the demolition of the existing structure. However, if encountered, existing below-ground utilities should be redirected around proposed structures. Existing utilities at an elevation to extend through the proposed footings should generally be sleeved and caulked to minimize the potential for moisture migration below the building slabs. Abandoned pipes exposed by grading should be securely capped or filled with minimum two-sack cement/sand slurry to help prevent moisture from migrating beneath foundation and slab soils. Comment Issue No. 12: The Geotechnical Consultant should provide the dynamic equivalent fluid unit weight for cantilevered and retrained retaining walls. Response: CTE/UES provides the following: If proposed, retaining walls backfilled using granular soils may be designed using the equivalent fluid unit weights given in Table 6.9 below. TABLE 6.9 EQUIVALENT FLUID UNIT WEIGHTS (Gh) (pounds per cubic foot) SLOPE BACKFILL WALL TYPE LEVEL BACKFILL 2:1 (HORIZONTAL: VERTICAL) CANTILEVER WALL 35 55 (YIELDING) RESTRAINED WALL 55 65 Lateral pressures on cantilever retaining walls (yielding walls) over six feet high due to earthquake motions may be calculated based on work by Seed and Whitman (1970). The total lateral earth pressure against a properly drained and backfilled cantilever retaining wall above the groundwater level can be expressed as : 1441 Montiel Road, Suite 115, Escondido, CA 92026 p. 760.746.4955 I oneues.com flUES~ Response to Second Round of Third Party Geotechnical Review Sales Building at Toyota Carlsbad Project No. 10-150296 Page4 For non-yielding (or "restrained") walls, the total lateral earth pressure may be similarly calculated based on work by Wood (1973): Where: PA/b = Static Active Earth Pressure= GhH2/2 PK/ b = Static Restrained Wall Earth Pressure= GhH2/2 l:!.PAdb = Dynamic Active Earth Pressure Increment= (3/8) kh yH2 l:!.PKdb = Dynamic Restrained Earth Pressure Increment= kh yH 2 b = unit length of wall (typically one foot) kh = 1/2 * PG Am Gh = Equivalent Fluid Unit Weight (given previously Table 6.9) H = Total Height of the retained soil y = Total Unit Weight of Soil:::: 135 pounds per cubic foot The static and increment of dynamic earth pressure in both cases may be applied with a line of action located at H/3 above the bottom of the wall (SEAOC, 2013). Additional Recommendations: In addition to the above response to comments, this document also provides updated geotechnical recommendations. Based on our understanding, pavement sections for frontage roads (Paseo Del Norte) were required. Based on the City of Carlsbad Structural Section of Streets and Alleys (Standard No. GS-17) and information given, the following pavement section appears suitable. All pavement-related work, at a minimum, should be completed in accordance with the current Standard Specifications for Public Works Construction, also known as the "Greenbook", and in accordance with industry standards. For new construction, all aggregate base materials and the upper 12 inches of subgrade materials should be compacted to a minimum relative compaction of 95 percent of the laboratory maximum, at or above the optimum moisture content, as determined by ASTM D 1557. 1441 Montiel Road, Suite 115, Escondido, CA 92026 p. 760.746.4955 I oneues.com flUES~ Response to Second Round of Third Party Geotechnical Review Sales Building at Toyota Carlsbad Project No. 10-150296 Page 5 PRELIMINARY RECOMMENDED PAVEMENT THICKNESS Asphalt Pavements Traffic Assumed Assumed AC Class II Area Traffic Subgrade Thickness Aggregate Base Index "R"-Value (inches) Thickness (inches) Paseo Del Norte 7.0 50 4.0 6.0 (Light Industrial) Please note that these pavement sections should be reviewed and modified or approved, as appropriate, by the governing authority. As an additional option, asphalt sections are likely to be appropriate if one-inch inch of aggregate base materials is substituted for ½-inch of asphalt concrete, if/as needed. Also, the City of Carlsbad and/or engineer/architect of record should review the assumed Traffic Index utilized in our pavement design to determine if a lower value could be considered for anticipated low frequency heavy vehicle use. We appreciate the opportunity to be of service on this project. Should you have any questions, please contact our office. The document is subject to the same limitations as the referenced geotechnical report. The opportunity to be of service is appreciated. If you have any questions, please contact our office. Respectfully, Universal Engineering Sciences (UES/CTE) Dan T. Math, GE #2665 Principal Engineer DTM :ach Appendix A Appendix B Appendix C References Response to Second Round of Third Party Geotechnical Review Ninyo & Moore Project No. 109343017, Dated August 1, 2023 City of Carlsbad BMP Design Manual (2023) Worksheets 1441 Montiel Road, Suite 115, Escondido, CA 92026 p. 760.746.4955 I oneues.com APPENDIX A REFERENCES REFERENCES Construction Testing and Engineering, Inc. 2023, Response to Third Party Geotechnical Review, Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California 92008, dated June 19. Universal Engineering Services, 2023, Grading Plans for Toyota of Carlsbad, 5424 Paseo Del Norte, Carlsbad, CA 92008. dated March 14. Construction Testing and Engineering, Inc., 2021a, Response to: The City of Carlsbad 1st Review for CDP 2020-0024 (DEV2020-0130), Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California, Job No. 10-15029G, dated January 19. Construction Testing and Engineering, Inc., 2021b, Additional Percolation Testing and Limited Infiltration Evaluation. Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California. Job No. 10-15029G, dated March 8. Construction Testing and Engineering, Inc. 2020, Response to: The City of Carlsbad 1st Review for CDP 2020-0024 (DEV2020-0130), Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California, Job No. 10-15029G, dated January 19. (Attached) Construction Testing and Engineering, Inc. 2019, Geotechnical Investigation, Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California, Job No. 10-15029G, dated August 2. APPENDIX B Response to Second Round of Third Party Geotechnical Review Ninyo & Moore Project No. 109343017, Dated August 1, 2023 Geotechnlcal & Envtronmtntal Sciences Consultants August 1, 2023 Project No. 109343017 Ms. Jessica Nishiura Hunsaker & Associates 9707 Waples Street San Diego, California 92121 Subject: Second Round of Third-Party Geotechnical Review Proposed Sales Building at Toyota Carlsbad 5434 Paseo Del Norte Carlsbad, California Dear Ms. Nishiura: At your request, we have prepared this letter providing our second round of review comments to the referenced geotechnical reports prepared by Construction Testing & Engineering, Inc. (CTE) dated August 2, 2019, January 30, 2020, and March 8, 2021 . Our original comments were prepared in the referenced Ninyo & Moore letter dated May 4, 2023. Based on our review of the most recent letter prepared by CTE dated June 19, 2023, the following comments remain: Closed Comment 1: Addressed in the CTE letter dated June 19, 2023. Closed Comment 2: Addressed in the CTE letter dated June 19, 2023. Closed Comment 3: Addressed in the CTE letter dated June 19, 2023. Closed Comment 4: Addressed in the CTE letter dated June 19, 2023. Closed Comment 5: Addressed in the CTE letter dated June 19, 2023. Closed Comment 6: Addressed in the CTE letter dated June 19, 2023. Comments 7 through 12 were not formally addressed in the CTE letter dated June 19, 2023. Accordingly, the following comments remain: Comment 7: The referenced geotechnical reports (CTE, 2019; 2021b) references the County of San Diego BMP Design Manual (2016). The Geotechnical Consultant should review the City of Carlsbad BMP Design Manual (2023) and provide updated recommendations and/or worksheets based on the City of Carlsbad BMP Design Manual (2023). Comment 8: The Geotechnical Consultant should provide a statement regarding the impact of the proposed grading and construction on adjacent properties and improvements. 5710 Ruffin Road I San Diego, California 921231 p 858.576.1000 I www.ninyoandmoore.com Comment 9: The project plans (Universal Engineering Services, 2023) show permeable pavers adjacent to the existing and proposed structures. The Geotechnical Consultant should comment on the suitability of the infiltration elements being adjacent to these structures and to provide recommendations for setbacks or mitigation measures, as appropriate. Additionally, the Geotechnical Consultant should also provide pervious pavement recommendations. Comment 10: The project plans (Universal Engineering Services, 2023) indicate the proposed improvements will span across fill and cut material of the old parafic deposits. The Geotechnical Consultant should provide recommendations for cut/fill transition. Comment 11: The project plans (Universal Engineering Services, 2023) indicate the existing structure will be demolished prior to construction of the new improvements. The Geotechnical Consultant should note any impacts to the recommendations for the new improvements. Comment 12: The Geotechnical Consultant should provide the dynamic equivalent fluid unit weight for cantilevered and restrained retaining walls. We appreciate the opportunity to be of service. Respectfully submitted, NINYO & MOORE ~m~ Christine M. Kuhns, PE Project Engineer CMK/JTK/mp Attachment: References 11::.::GE Principal Engineer Ninyo & Moore I 5434 Paseo Del Norte, Carlsbad, California I 109343017 I August 1, 2023 2 REFERENCES City of Carlsbad, 1993, Technical Guidelines For Geotechnical Reports: dated January. City of Carlsbad, 2023, BMP Design Manual: dated January 11. Construction Testing and Engineering, Inc., 2019, Geotechnical Investigation, Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California, Job No. 10-15029G, dated August 2. Construction Testing and Engineering, Inc., 2020a, Response to: The City of Carlsbad 1st Review for COP 2020-0024 (DEV2020-0130), Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California, Job No. 10-15029G, dated January 19. Construction Testing and Engineering, Inc., 2020b, Updated to Geotechnical Investigation, Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California, CTE Job No, 10-15-29G: dated January 30. Construction Testing and Engineering, Inc., 2021 a, Response to: The City of Carlsbad 1st Review for CDP 2020-0024 (DEV2020-0130), Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California, Job No. 10-15029G, dated January 19. Construction Testing and Engineering, Inc., 2021 b, Additional Percolation Testing and Limited Infiltration Evaluation, Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California, Job No. 10-15029G, dated March 8. Ninyo & Moore, 2023, Third-Party Geotechnical Review, Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California 92008: dated May 4. Universal Engineering Services, 2023, Grading Plans for Toyota of Carlsbad, 5424 Paseo Del Norte, Carlsbad, CA 92008: dated March 14. Ninyo & Moore I 5434 Paseo Del Norte. Carlsbad, California I 109343017 I August 1 2023 1 APPENDIX C City of Carlsbad BMP Design Manual (2023) Worksheets Appendix D: Geotechnical Engineer Analysis Appendix D Geotechnical Engineer Analysis .1 Analysis of • tration estrictions This section is only applicable if the analysis of infiltration restrictions is performed by a licensed engineer practicing in geotechnical engineering. The SWQMP Preparer and Geotechnical Engineer must work collaboratively to identify any infiltration restrictions identified in Table D.1-1 below. Upon completion of this section, the Geotechnical Engineer must characterize each DMA as Restricted or Unrestricted for infiltration and provide adequate support/ discussion in the geotechnical report. A DMA is considered restricted when one or more restrictions exist which cannot be reasonably resolved through site design changes. Table D.1-1: Considerations for Geotechnical Analysis of Infiltration Restrictions Mandatory Considerations Optional Considerations Result Restriction Element B:MP is within 100' of Contaminated Soils BMP is within 100' of Industrial Activities Lacking Source Control BMP is within 100' of Well/ Groundwater Basin BMP is within 50' of Septic Tanks/Leach Fields BMP is within 10' of Structures/Tanks/Walls BMP is within 10' of Sewer Utilities BMP is within 10' of Groundwater Table BMP is within Hydric Soils BMP is within Highly Liquefiable Soils and has Connectivity to Structures BMP is within 1.5 Times the Height of Adjacent Steep Slopes (2'.25%) County Staff has Assigned ''Restricted" Infiltration Category BMP is within Predominantly Type D Soil BMP is within 10' of Property Line BMP is within Fill Depths of 2'.5' (Existing or Proposed) BMP is within 10' of Underground Utilities BMP is within 250' of Ephemeral Stream Other (Provide detailed geotechnical support) Based on examination of the best available information, Is Element Applicable? (Yes/No) X □ I have not identified any restrictions above. Unrestricted Based on examination of the best available information, Ci! I have identified one or more restrictions above. Restricted Table D.1-1 1s divided into Mandatory Considerations and Optional Considerations. Mandatory D-1 Jan.2023 Appendix D: Geotechnical Engineer Analysis Considerations include elements that may pose a significant risk to human health and safety and must always be evaluated. Optional Considerations include elements that are not necessarily associated with human health and safety, so analysis is not mandated through this guidance document. All elements presented in this table are subject to the discretion of the Geotechnical Engineer if adequate supporting information is provided. Applicants must evaluate infiltration restrictions through use of the best available data. A list of resources available for evaluation is provided in Section B.2 D.2 Determination of Design Infiltration Rates This section is only applicable if the determination of design infiltration rates is performed by a licensed engineer practicing in geotechnical engineering. The guidance in this section identifies methods for identifying observed infiltration rates, corrected infiltration rates, safety factors, and design infiltration rates for use in structural BMP design. Upon completion of this section, the Geotechnical Engineer must recommend a design infiltration rate for each DMA and provide adequate support/ discussion in the geotechnical report. Table D.2-1: Elements for Determination of Design Infiltration Rates Initial Infiltration Rate Identify per Section D.2.1 0.42 in/hr Corrected Infiltration Rate Identify per Section D.2.2 in/hr Safety Factor unitless Identify per Section D .2.3 2.0 Design Infiltration Rate in/hr Corrected Infiltration Rate+ Safety Factor 0.21 D-2 Jan.2023 Appendix D: Geotechnical Engineer Analysis D.2.1 Initial Infiltration Rate For purposes of this manual, the initial infiltration rate is the infiltration rate that has been identified based on the initial testing methods. Some of the acceptable methods for determining initial infiltration rates are presented in Table D.2-2 below, though other testing methods may be acceptable as evaluated by the geotechnical engineer. This table identifies what methods require application of correction factors, safety factors, and what BMPs types are ultimately acceptable for each testing method. The geotechnical engineer should use professional discretion when selecting a testing method as it may ultimately impact the types of BMPs that are permitted. Table D.2-2: Acceptable Initial Infiltration Rate Methods A •"••-~· """ ... Desktop Methods* NRCS Soil Survey Maps Grain Size Analysis Correlation Cone Penetrometer Methods Tescing Percolation Tests Infiltration Tests ,__ _______ _ Laboratory Permeability Tests Simple Open Pit Test Open Pit Falling Head Test Well Permeameter Method Borehole Percolation Tests Double Ring Infiltrometer Test Single Ring Infiltrometer Test Large-scale Pilot Infiltration Test Smaller-scale Pilot Infiltration Test Not Applicable Not Applicable Required (See Section D.2.2) Not Applicable D-3 ~ ..... ~ Not Applicable Required (See Section D.2.3) Required (See Section D.2.3) Required (See Section D.2.3) --.. l i[i1 I I '· •• I J!.I """ ~ ____. ... BMPs with Underdrains BMPs with Underdrains AnyBMPType AnyBMPType Jan.2023 Appendix D: Geotechnical Engineer Analysis *Desktop methods may be performed without a geotechnical engineer. Refer to Basic Infiltration Analysis guidance in Section B.2.3 for more information. NRCS Soil Survey Maps: NRCS Soil Survey maps can be used to establish approximate infiltration rates for use in BMP design. Under this method, default design infiltration rates may be applied based on the predominant NRCS soil type present within a proposed BMP location. Default design infiltration rates (in/hr) for each NRCS soil type are: A=0.300, B=0.200, C=0.100, D=0.025, Restricted=0.000. Use of these default design infiltration rates does not require application of any correction factors or safety factors. Grain Size Analysis Testing: Hydraulic conductivity can be estimated indirectly from correlations with soil grain-size distributions. While this method is approximate, correlations have been relatively well established for some soil conditions. One of the most commonly used correlations between grain size parameters and hydraulic conductivity is the Hazen (1892, 1911) empirical formula (Philips and Kitch, 2011), but a variety of others have been developed. Correlations must be developed based on testing of site-specific soils. For purposes of this manual, saturated hydraulic conductivity and infiltration rate can be assumed to be equal. Cone Penetrometer Testing: Hydraulic conductivity can be estimated indirectly from cone penetrometer testing (CPI). A cone penetrometer test involves advancing a small probe into the soil and measuring the relative resistance encountered by the probe as it is advanced. The signal returned from this test can be interpreted to yield estimated soil types and the location of key transitions between soil layers. If this method is used, correlations must be developed based on testing of site- specific soils. For purposes of this manual, saturated hydraulic conductivity and infiltration rate can be assumed to be equal. Laboratory Permeability Testing: Laboratory testing can be performed to help evaluate the infiltration rates. The laboratory tests should be in accordance with ASTM or other approved procedures (e.g. ASTM D 5084 or D 5856). Several tests may be required from samples at different elevations to help evaluate the permeability characteristics of the soil strata. Simple Open Pit Test: The Simple Open Pit Test is a falling head test in which a hole at least two feet in diameter is filled with water to a level of 6" above the bottom. Water level is checked and recorded regularly until either an hour has passed or the entire volume has infiltrated. The test is repeated two more times in succession and the rate at which the water level falls in the third test is used as the infiltration rate. This test identifies a percolation rate that should be converted to an infiltration rate using the Porchet method. Open Pit Falling Head Test: This test is similar to the Simple Open Pit Test, but covers a larger footprint, includes more specific instructions, returns more precise measurements, and generally should be overseen by a geotechnical professional. Nonetheless, it remains a relatively simple test. D-4 Jan.2023 Appendix D: Geotechnical Engineer Analysis To perform this test, a hole is excavated at least 2 feet wide by 4 feet long Oarger is preferred) and to a depth of at least 12 inches. The bottom of the hole should be approximately at the depth of the proposed infiltrating surface of the BMP. The hole is pre-soaked by filling it with water at least a foot above the soil to be tested and leaving it at least 4 hours (or overnight if clays are present). After pre- soaking, the hole is refilled to a depth of 12 inches and allow it to drain for one hour (2 hours for slower soils), measuring the rate at which the water level drops. The test is then repeated until successive trials yield a result with less than 10 percent change. Well Permeameter Method (USBR 7300-89): Well permeameter methods were originally developed for purposes of assessing aquifer permeability and associated yield of drinking water wells. This family of tests is most applicable in situations in which infiltration facilities will be placed substantially below existing grade, which limits the use of surface testing methods. In general, this test involves drilling a 6 inch to 8 inch test well to the depth of interest and maintaining a constant head until a constant flow rate has been achieved. Water level is maintained with down- hole floats. A smaller diameter boring may be adequate, however this then requires a different correction factor to account for the increased variability expected. The Porchet method or the nomographs provided in the USBR Drainage Manual (United States Department of the Interior, Bureau of Reclamation, 1993) are used to convert the measured rate of percolation to an estimate of vertical hydraulic conductivity. While these tests have applicability in screening level analysis, considerable uncertainty is introduced in the step of converting direct percolation measurements to estimates of vertical infiltration. Additionally, this testing method is prone to yielding erroneous results cases where the vertical horizon of the test intersects with minor lenses of sandy soils that allow water to dissipate laterally at a much greater rate than would be expected in a full-scale facility. To improve the interpretation of this test method, a continuous bore log should be inspected to determine whether thin lenses of material may be biasing results at the strata where testing is conducted. Consult USBR procedure 7300-89 for more details. Source: (United States Department of the Interior, Bureau of Reclamation, 1990, 1993) Borehole Percolation Tests: Borehole percolation tests were originally developed as empirical tests to estimate the capacity of onsite sewage disposal systems (septic system leach fields), but have more recently been adopted into use for evaluating storm water infiltration. Similar to the well permeameter method, borehole percolation methods primarily measure lateral infiltration into the walls of the boring and are designed for situations in which infiltration facilities will be placed well below current grade. The percolation rate obtained in this test should be converted to an infiltration rate using a technique such as the Porchet method. This test is generally implemented similarly to the USBR Well Permeameter Method. Per the Riverside D-5 Jan.2023 Appendix D: Geotechnical Engineer Analysis County Borehole Percolation method, a hole is bored to a depth at least 5 times the borehole radius. The hole is presoaked for 24 hours (or at least 2 hours if sandy soils with no clay). The hole is filled to approximately the anticipated top of the proposed infiltration basin. Rates of fall are measured for six hours, refilling each half hour (or 10 minutes for sand). Tests are generally repeated until consistent results are obtained. The same limitations described for the well permeameter method apply to borehole percolation tests, and their applicability is generally limited to initial screening. To improve the interpretation of this test method, a continuous soil core can be extracted from the hole and below the test depth, following testing, to determine whether thin lenses of material may be biasing results at the strata where testing is conducted. Sources: Riverside County Percolation Test (2011), California Test 750 (Caltrans, 1986), San Bernardino County Percolation Test (1992); USEPA Falling Head Test (USEPA, 1980). In comparison to a double-ring infiltrometer, this test has the advantage of measuring infiltration over a larger area and better resembles the dimensionality of a typical small scale BMP. This test identifies a percolation rate that should be converted to an infiltration rate using the Porchet method. However, if this method is used to identify rates for a drywell BMP, the correction factor can be omitted at the discretion of the geotechnical engineer. Double Ring Infiltrometer Test (ASTM 3385): The Double Ring Infiltrometer was originally developed to estimate the saturated hydraulic conductivity of low permeability materials, such as clay liners for ponds, but has seen significant use in storm water applications. The most recent revision of this method from 2009 is known as ASTM 3385-09. The testing apparatus is designed with concentric rings that form an inner ring and an annulus between the inner and outer rings. Infiltration from the annulus between the two rings is intended to saturate the soil outside of the inner ring such that infiltration from the inner ring is restricted primarily to the vertical direction. To conduct this test, both the center ring and annulus between the rings are filled with water. There is no pre-wetting of the soil in this test. However, a constant head of 1 to 6 inches is maintained for 6 hours, or until a constant flow rate is established. Both the inner flow rate and annular flow rate are recorded, but if they are different, the inner flow rate should be used. There are a variety of approaches that are used to maintain a constant head on the system, including use of a Mariotte tube, constant level float valves, or manual observation and filling. This test must be conducted at the elevation of the proposed infiltrating surface; therefore application of this test is limited in cases where the infiltration surface is a significant distance below existing grade at the time of testing. This test is generally considered to provide a direct estimate of vertical infiltration rate for the specific point tested and is highly replicable. However, given the small diameter of the inner ring (standard diameter is 12 inches, but it can be larger), this test only measures infiltration rate in a small area. D-6 Jan.2023 Appendix D: Geotechnical Engineer Analysis Additionally, given the small quantity of water used in this test compared to larger scale tests, this test may be biased high in cases where the long term infiltration rate is governed by groundwater mounding and the rate at which mounding dissipates (i.e., the capacity of the infiltration receptor). Finally, the added effort and cost of isolating vertical infiltration rate may not necessarily be warranted considering that BMPs typically have a lateral component of infiltration as well. Therefore, while this method has the advantages of being technical rigorous and well standardized, it should not necessarily be assumed to be the most representative test for estimating full-scale infiltration rates. Source: American Society for Testing and Materials (ASTM) International (2009). Single Ring Infiltrometer Test: The single ring infiltrometer test is not a standardized ASTM test, however it is a relatively well-controlled test and shares many similarities with the ASTM standard double ring infiltrometer test (ASTM 3385-09). This test is a constant head test using a large ring (preferably greater than 40 inches in diameter) usually driven 12 inches into the soil. Water is ponded above the surface. The rate of water addition is recorded and infiltration rate is determined after the flow rate has stabilized. Water can be added either manually or automatically. The single ring used in this test tends to be larger than the inner ring used in the double ring test. Driving the ring into the ground limits lateral infiltration; however some lateral infiltration is generally considered to occur. Experience in Riverside County (CA) has shown that this test gives results that are close to full-scale infiltration facilities. The primary advantages of this test are that it is relatively simple to conduct and has a larger footprint ( compared to the double-ring method) and restricts horizontal infiltration and is more standardized (compared to open pit methods). However, it is still a relatively small scale test and can only be reasonably conducted near the existing ground surface. Large Scale Pilot Infiltration Test: As its name implies, this test is closer in scale to a full-scale infiltration facility. This test was developed by Washington State Department of Ecology specifically for storm water applications. To perform this test, a test pit is excavated with a horizontal surface area of roughly 100 square feet to a depth that allows 3 to 4 feet of ponding above the expected bottom of the infiltration facility. Water is continually pumped into the system to maintain a constant water level (between 3 and 4 feet about the bottom of the pit, but not more than the estimated water depth in the proposed facility) and the flow rate is recorded. The test is continued until the flow rate stabilizes. Infiltration rate is calculated by dividing the flow rate by the surface area of the pit. This test has the advantage of being more resistant to bias from localized soil variability and being more similar to the dimensionality and scale of full scale BMPs. It is also more likely to detect long term decline in infiltration rates associated with groundwater mounding. As such, it remains the preferred test for establishing design infiltration rates in Western Washington (Washington State Department of Ecology, 2012). In a comparative evaluation of test methods, this method was found to provide a more reliable estimate of full-scale infiltration rate than double ring infiltrometer and D-7 Jan.2023 Appendix D: Geotechnical Engineer Analysis borehole percolation tests (Philips and Kitch 2011). The difficulty encountered in this method is that it requires a larger area be excavated than the other methods, and this in turn requires larger equipment for excavation and a greater supply of water. However, this method should be strongly considered when less information is known about spatial variability of soils and/ or a higher degree of certainty in estimated infiltration rates is desired. Smaller-Scale Pilot Infiltration Test: The smaller-scale PIT is conducted similarly to the large-scale PIT but involves a smaller excavation, ranging from 20 to 32 square feet instead of 100 square feet for the large-scale PIT, with similar depths. The primary advantage of this test compared to the full- scale PIT is that it requires less excavation volume and less water. It may be more suitable for small- scale distributed infiltration controls where the need to conduct a greater number of tests outweighs the accuracy that must be obtained in each test, and where groundwater mounding is not as likely to be an issue. D.2.2 Corrected Infiltration Rate For purposes of this manual, the corrected infiltration rate is the initial infiltration rate as modified by appropriate correction factors needed to convert from percolation to infiltration or to correct for effects of water temperature. The sections below present discussion on correction factors that should be considered by the Geotechnical Engineer. D.2.2.1 Percolation Rate Correction Factor A common misunderstanding is that the "percolation rate" obtained from a percolation test is equivalent to the "infiltration rate" obtained from tests such as a single or double ring infiltrometer test which is equivalent to the "saturated hydraulic conductivity". In fact, these terms have different meanings. Saturated hydraulic conductivity is an intrinsic property of a specific soil sample under a given density. It is a coefficient in Darcy's equation (Darcy 1856) that characterizes the flux of water that will occur under a given gradient. The measurement of saturated hydraulic conductivity in a laboratory test is typically referred to as "permeability", which is a function of the density, structure, stratification, fines, and discontinuities of a given sample under given controlled conditions. In contrast, infiltration is the downward entry of water into the soil. The velocity at which water enters the soil is infiltration rate. Infiltration rate is typically expressed in inches per hour. For the purposes of this manual, saturated hydraulic conductivity and infiltration rate can be assumed to be equal. Similarly, to permeability, infiltration rate can be limited by a number of factors including the layering of soil, density, discontinuities, and initial moisture content. These factors control how quickly water can move through a soil. However, infiltration rate can also be influenced by mounding of groundwater, and the rate at which water dissipates horizontally below a BMP -both of which describe the "capacity'' of the "infiltration receptor" to accept this water over an extended period. For this reason, an infiltration test should ideally be conducted for a relatively long duration resembling a series of storm events so that the capacity of the infiltration receptor is evaluated as well as the rate at D-8 Jan.2023 Appendix D: Geotechnical Engineer Analysis which water can enter the system. Infiltration rates are generally tested with larger diameter holes, pits, or apparatuses intended to enforce a primarily vertical direction of flux. In contrast, percolation is tested with small diameter holes, and it is mostly a lateral phenomenon. The direct measurement yielded by a percolation test tends to overestimate the infiltration rate, except perhaps in cases in which a BMP has similar dimensionality to the borehole, such as a dry well. Adjustment of percolation rates may be made to an infiltration rate using a technique such as the Porchet Method. For drywell BMPs this adjustment may be determined per other methods, (i.e. USBR 7300-89), or may be omitted entirely at the discretion of the geotechnical engineer. Percolation Rate Conversion Example Problem: Apply the Porchet Method (Inverse Borehole Method) to determine the corrected infiltration rate from the following inputs: • Total depth of test hole, DT = 60 inches • Initial depth to water, D 0 = 12.25 inches • Final depth to water, Dr= 13.75 inches • Test hole radius, r = 4 inches • Time interval, ~t = 10 minutes D-9 Jan.2023 Appendix D: Geotechnical Engineer Analysis Solution: 1. Solve for the height of water at the beginning of the selected time interval, Ho: Ho = Dr -Do = 60 -12.25 = 47.75 inches 2. Solve for the height of water at the end of the selected time interval, Hf: Hf= DT-Df = 60-13.75 = 46.25 inches 3. Solve for the change in height of water over the selected time interval, ~: M-I = HO -Hf= 47.75 -46.25 = 1.50 inches 4. Calculate the average head over the selected time interval, Havg: Havg = (Ho + Hf)/2 = (47.75 + 46.25)/2 = 47.00 inches 5. Calculate the tested infiltration rate, It, using the following equation: It= (M-!*60:oi<r) / (.6.t*(r+2Havg)) It= (1.50 in* 60 min/hr* 4 in)/ (10 min* (4 inch+ (2 * 47 in))) = 0.37 in/hr D.2.2.2 Temperature Correction Factor The rate of infiltration through soil is affected by the viscosity of water, which in turn is affected by the temperature of water. As such, infiltration rate is strongly dependent on the temperature of the infiltrating water (Cedergren, 1997). For example, Emerson (2008) found that wintertime infiltration rates below a BMP in Pennsylvania were approximately half their peak summertime rates. As such, it is important to consider the effects of temperature when planning tests and interpreting results. If possible, testing should be conducted at a temperature that approximates the typical runoff temperatures for the site during the ti.mes when rainfall occurs. If this is not possible, then the results of infiltration tests should be adjusted to account for the difference between the temperature at the ti.me of testing and the typical temperature of runoff when rainfall occurs. The measured infiltration can be adjusted by the ratio of the viscosity at the test temperature versus the typical temperature when rainfall occurs (Cedergren, 1997), per the following formula: D-10 Jan.2023 Appendix D: Geotechnical Engineer Analysis K = K x ( µTest ] Typical Test µTypical Where: KTypical = the typical infiltration rate expected at typical temperatures when rainfall occurs KTest = the infiltration rate measured or estimated under the conditions of the test µTypical = the viscosity of water at the typical temperature expected when rainfall occurs µTest = the viscosity of water at the temperature at which the test was conducted D.2.3 Safety Factors A safety factor between 2.0 and 9.0 must be applied to the infiltration rates determined above1• Application of a safety factor reduces initial or corrected infiltration rates in order to account for various considerations that can impact infiltration rates measured rates over time. In order to minimize safety factor impacts, applicants should consider performing rigorous site investigation, incorporating pretreatment and resiliency into the site design, and taking steps to reduce incidental compaction within BMP footprints. If the proposed BMP utilizes an underdrain, a default safety factor of 2.0 may be applied or a more detailed safety factor may be determined per Table D.2-3. If the proposed BMP does not utilize an underdrain, then the safety factor must be determined through completion of Table D.2-3. 1 Use of default design infiltration rates based on NRCS soil type does not require application of safety factor. D-11 Jan.2023 .... ..... ... l_.l'lilL"ilr1,:..-. ••Ill Suitability Assessment (A) Design (B) Appendix D: Geotechnical Engineer Analysis Table D.2-3: Determination of Safety Factor -.... r:irnrm;a 1, . .... 1 llilil! rrrili • -~ ........ .... ... .. :••l'HII • ' -...... Infiltration Testing Method 0.25 1 0.25 Soil Texture Class 0.25 Ra er to 0.50 Soil Variability 0.25 Tab~D.2-4 0.50 Depth to Groundwater/Obstruction 0.25 2 0.50 Suitability Assessment Safety Factor, SA = ~P 1.75 Pretreatment 0.50 1 0.50 Resiliency 0.25 Refer to Ta~e D.2-4 0.50 Compaction 0.25 1 0.25 Design Safety Factor, SB = ~P 1.25 Safety Factor, S = SA x SB 2.2 (Must be always greater than or equal to 2) The geotechnical engineer should reference Table D.2-4 below in order to determine appropriate factor values for use in the table above. The values in the table below are subjective in nature and the geotechnical engineer may use professional discretion in how the points are assigned. D-12 Jan.2023 -.. ---1 11..."11 llwlll'.11 I I Infiltration Testing Method Soil Texture Class Soil Variability Depth to Groundwater/ Obstruction Pretreatment Resiliency Compaction Appendix D: Geotechnical Engineer Analysis Table D.2-4: Guidance for Determining Individual Factor Values ~;-;;., .. _. -----,. J~ .... ~ .... , ........... . I -· -=-...... • ft ---.... -ms .ft -·--111■■■■ .... -----11 1--1111■■■-------U!lllllll .... ... .... .... ... .... ...... ... At least 4 tests within BMP At least 2 tests of any kind footprint, OR Large/Small Any within 50' ofBMP. Scale Pilot Infiltration Testing over at least 5% of BMP footprint. Unknown, Silty, Loamy Granular/ Slightly Loamy or Clayey Unknown or Moderately Homogeneous Significantly Homogeneous High <5' below BMP 5-15' below BMP >15' belowBMP Provides good pretreatment Provides excellent pretreatment None/Minimal OR does not receive significant OR only receives runoff from runoff from unpaved areas rooftops and road surfaces. Includes underdrain/backup Includes underdrain/backup None/Minimal drainage that ensures ponding drainage AND supports easy draws down in <96 hours restoration of impacted infiltration rates. Moderate Low Likelihood Very Low Likelihood Likelihood D-13 Jan.2023 Appendix D: Geotechnical Engineer Analysis D.3Geotechnical Reporting Requirements This section is only applicable if a licensed engineer practicing in geotechnical engineering has performed the determination of infiltration restrictions and/ or design infiltration rates. The geotechnical report must document the following items in the geotechnical report. • Date of site analysis • Scope and results of testing • Public health and safety requirements that affect infiltration locations o Must address Mandatory Considerations presented in Appendix D.1 • Conclusions o Characterize DMAs as Restricted or Unrestricted for Infiltration o Identify Design Infiltration Rates for DMAs • Correspondence between City Staff and Geotechnical Engineer (if applicable) o Development status of site prior to the project application (i.e. new development with raw ungraded land, or redevelopment with existing graded conditions) o The history of design discussions for the site proposed project o Site design alternatives considered to achieve infiltration or partial infiltration on site o Physical impairments and public safety concerns (i.e. fire road egress, sewer lines, etc) o The extent low impact development BMP requirements were included in the project design It is ultimately the responsibility of the SWQMP Preparer (not the geotechnical engineer) to interpret the conclusions made in the geotechnical report and ensure they are appropriately supported/ reflected in associated SWQMP submittal materials such as checklists, narratives, calculations, exhibits, and supplemental reports. D-14 Jan.2023 Appendix D: Geotechnical Engineer Analysis Blank Page for 2-sided formattingpurposes D-15 Jan.2023 September 14, 2023 Toyota Carlsbad 5424 Paseo Del Norte Carlsbad, California 92008 Attention: Mr. Kevin Carroll (760) 496-2931 kcarroll@lexuscarlsbad.com Universal Engineering Sciences (UES) 1441 Montiel Road, Suite 115 Escondido, CA 92026 p. 760.746.4955 I TeamUES.com UES/CTE Job No. 10-15029G cc: silas.perks@civillandworks.com dave@civillandworks.com sitanant@gc-se.com Subject: Reference: Dear Mr. Carroll Review of Retaining Wall Drawings and Foundation Details Proposed Sales Building at Toyota Carlsbad 5434 Paseo Del Norte, Carlsbad, California 92008 End of Document (Appendix A) At your request, Universal Engineering Sciences (UES/CTE) has reviewed the retaining wall drawings and foundation details for the referenced project. The object of our review was to identify potential conflicts with the recommendations presented in our referenced geotechnical report. It is our conclusion that the reviewed plans are in general conformance with recommendations presented in the referenced soils report. Should you have any questions or need further information please do not hesitate to contact this office. We appreciate the opportunity to be of service on this project. Should you have any questions, please contact our office. The document is subject to the same limitations as the referenced geotechnical report. The opportunity to be of service is appreciated. If you have any questions, please contact our office. Respectfully, Universal Engineering Sciences (UES/CTE) Dan T. Math, GE #2665 Principal Engineer DTM:ach Appendix A References Environmental Consulting I Geotechnical Engineering I Materials Testing & Inspections Occupational Health & Safety I Building Sciences & Code Compliance I Virtual Design Consulting APPENDIX A REFERENCES REFERENCES Universal Engineering Services, 2023, Grading Plans for Toyota of Carlsbad, 5424 Paseo Del Norte, Carlsbad, CA 92008. dated March 14. Grimm+ Chen Structural Drawings (9 Sheets), 2023, Grading Plans for Toyota of Carlsbad, 5424 Paseo Del Norte, Carlsbad, CA 92008. dated September 5. Construction Testing and Engineering, Inc., 2021b, Additional Percolation Testing and Limited Infiltration Evaluation. Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California. Job No. 10-15029G, dated March 8. Construction Testing and Engineering, Inc. 2019, Geotechnical Investigation, Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California, Job No. 10-15029G, dated August 2. Construction Testing and Engineering, Inc. 2020, Update to Geotechnical Investigation, Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California, Job No. 10-15029G, dated January 30. C En~ineering Construction Testing & Engineering, Inc. ©) A Universal SCc,ences Inspection I Testing I Geotechnical I Environmental & Construction Engineering I Civil Engineering I Surveying ompany June 19, 2023 Toyota Carlsbad Attention: Mr. Kevin Carroll 5424 Paseo Del Norte Carlsbad, California 92008 Telephone: (760) 496-2931 Subject: Response to Third Party Geotechnical Review Proposed Sales Building at Toyota Carlsbad CTE Job No. 10-15029G Via Email: kcarroll@lexuscarlsbad.com 5434 Paseo Del Norte, Carlsbad, California 92008 Ninyo & Moore Project No. 109343017, Dated May 4, 2023 Reference: Appendix A Mr. Carroll: As requested, Construction Testing & Engineering, Inc. (CTE) provides the following response to the Third Party Geotechnical Review by Ninyo & Moore dated May 4, 2023. The responses provided below and are numbered based on the Comment Numbers. A copy of the Third Party Geotechnical Review is provided as Attachment 1. Comment 1: The Geotechnical Consultant should review the project grading and foundation plans and provide any additional geotechnical recommendations as appropriate, and indicate if the plans have been prepared in accordance with the geotechnical recommendations provided in the referenced geotechnical reports (CTE, 2019, 2021b). Response to Comment 1: Construction Testing & Engineering, Inc. (CTE) has reviewed the geotechnical aspects of the referenced plans for the subject project. The object of our review was to identify potential conflicts with the recommendations presented in the referenced geotechnical document, as they pertain to the proposed improvements. It is our conclusion that the reviewed plans are in substantial conformance with recommendations presented in the referenced soils report. Comment 2: The CTE report dated January 30, 2020 was referenced in the CTE letter dated March 8, 2019, but was not included in the review package We request that a copy of the CTE report dated January 30, 2020 be provided for us to review. Response to Comment 2: The referenced CTE report dated January 30, 2020 has been attached for your review as Attachment 2. 1441 Montiel Road, Suite 115 I Escondido, CA 92026 I Ph (760) 746-4955 I Fax (760) 746-9806 I www.cte-inc.net Response to Third Party Geotechnical Review Proposed Sales Building at Toyota Carlsbad 5434 Paseo Del Norte, Carlsbad, California June 19, 2023 Page2 CTE Job No. 10-15029G Comment 3: Per the City of Carlsbad (1993) guidelines, the Geotechnical Consultant should provide a geotechnical cross-section of the site. Additionally, an updated geotechnical map/plot plan showing the location of the cross-section should be provided. Response to Comment 3: An updated geotechnical map with CTE' s geotechnical exploration locations and cross section is provided on the attached Figure 2 with the most current grading plan as the base map. In addition, a geologic cross section has been provided on the attached Figure 2A. Comment 4: Per the City of Carlsbad (1993) guidelines, the Geotechnical Consultant should provide a geologic map. Response to Comment 4: Per the City of Carlsbad (1993) guidelines, a geologic map has been attached (Figure 3). Comment 5: The Geotechnical Consultant should show the lateral limits of the recommended remedial grading on the geologic/geotechnical map. Specifically, with regards to impacts to existing improvements/structures. Response to Comment 5: The approximate limits of remedial grading is depicted on the attached Figure 2. Comment 6: The referenced geotechnical report (CTE, 2019) utilizes the standards provided by the 2016 California Building Code (CBC) and American Society of Civil Engineers (ASCE) 7-10. As the standards of the 2022 CBC and ASCE 7-16 are the currently accepted practices, the Geotechnical Consultant should update the report and applicable sections utilizing those standards. Response to Comment 6: The following updated parameters are provided: The seismic ground motion values listed in the table below were derived in accordance with the ASCE 7-16 Standard. This was accomplished by establishing the Site Class based on the soil properties at the site. Site coefficients and parameters were calculated using the SEAOC-OSHPD U.S. Seismic Design Maps application. These values are intended for the design of structures to resist the effects of earthquake ground motions based on the site coordinates of 33.1329° latitude and-117.3255° longitude, as underlain by soils corresponding to site Class C. \\file0l.cte.cte-inc.net\CTE Share\Projects\10-15000 to 10-15999 Projects\10-15029G\Geo Report-Letters\Ltr_Response to Review Comments -6.2023.doc Response to Third Party Geotechnical Review Proposed Sales Building at Toyota Carlsbad 5434 Paseo Del Norte, Carlsbad, California June 19, 2023 TABLE 1 Page 3 CTE Job No. 10-15029G SEISMIC GROUND MOTION VALUES (CODE-BASED) 2019 CBC AND ASCE 7-16 PARAMETER VALUE 2019 CBC/ASCE 7-16 REFERENCE Site Class C ASCE 16, Chapter 20 Mapped Spectral Response 1.088 Figure 1613.2.1 (1) Acceleration Parameter, Ss Mapped Spectral Response 0.393 Figure 1613.2.1 (2) Acceleration Parameter, S1 Seismic Coefficient, Fa 1.200 Table 1613.2.3 (1) Seismic Coefficient, Fv 1.500 Table 1613.2.3 (2) MCE Spectral Response 1.306 Section 1613.2.3 Acceleration Parameter, SMs MCE Spectral Response 0.589 Section 1613.2.3 Acceleration Parameter, SM1 Design Spectral Response 0.871 Section 1613.2.5(1) Acceleration, Parameter Sos Design Spectral Response 0.393 Section 1613 .2.5 (2) Acceleration, Parameter Sm Peak Ground Acceleration PGAM 0.578 ASCE 16, Section 11.8.3 This letter is subject to the same limitations as the previously prepared geotechnical documents. We appreciate the opportunity to be of service on this project. Should you have any questions or need further information please do not hesitate to contact this office. Respectfully submitted, CONSTRUCTION TESTING & ENGINEERING, INC. Dan T. Math, GE #2665 Principal Engineer MB/DTM:ach ~15~ Michael Balagtas Project Engineer \\file0l.cte.cte-inc.net\CTE Share\Projects\10-15000 to 10-15999 Projects\10-15029G\Geo Report-Letters\Ltr_Response to Review Comments -6.2023.doc Response to Third Party Geotechnical Review Proposed Sales Building at Toyota Carlsbad 5434 Paseo Del Norte, Carlsbad, California June 19, 2023 Figure 2 Geologic/Exploration Map Figure 2A Geologic Cross Sections Figure 3 Geologic Map Appendix A: References Page4 CTE Job No. 10-15029G Attachment 1 Response to Third Party Geotechnical Review, Ninyo & Moore Project No. 109343017, Dated May 4, 2023 Attachment 2 Update to Geotechnical Investigation, Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California, CTE Job No. 10-15029G, Dated January 30, 2020. \\file0l.cte.cte-inc.net\CTE Share\Projects\10-15000 to 10-15999 Projects\10-15029G\Geo Report-Letters\Ltr_Response to Review Comments -6.2023.doc < N N 0, m s-4~ Approximate Boring Location Approximate Percolation Test Location Quaternary Old Paralic Deposits over Tertiary Santiago Formation 25' : '/ I I I I I I I I FF=75.1 PA~=74. I I I I B-3 J ~( --- f'--, I I I I I I I I I I I I Tsa 1 I I I i el I I I I I I I I I I I I I I I I 5lJ4PAS£0DELNam 21H)60-02 ~ ~ P-4~ .s i Qop § Tsa ~1--------------------------------------"T-----------------------------... ...., .... ----1 I C~ I:.,~;;::~~~ Construction Testing & Engineering, Inc. GEOLOGJ~ii,~~~~~ SALE~~!f ON MAPml'll""'"-----t _ ~ ~~~~';~y Inspection I Testv,g I Geotectrieal I Environmental&CoostructionEngneef'ing I CM~ I Surve)VIQ 5434-PASIO DEL NORTE ~ CARJmlAD, CALIFORNIA .;;._ _________________________________________________________________________ .. 90 .--------,-------,-----,-------,-------,-----,--------,.------,------,----1 ~ ~UILUIN' WALL 80 1----------,f---l/.c-_lt+------+-----+-----+-----+-----+-----f----------,---i LAND CAPE ~, --dl+------+-------+='=B-4F_'-=c~~-+-~B-=i=-3----+-------+------+------+---< "' EX. BUILDING r--..._ I\ 2.Dl Ff,= 75.13 -; 1-----+~-~?-~~l~'----=--\-f :::L='Q=p¢~---+--=-==--==1-=:i=~=~Q=p=pf.==fa~-=~ PP¢ 2 \ I 70 l--------,6""~CU~R~B~-=i;=~~Cop:P'CC-W~lc-"--t------t-lr----::Q~op:--l---t-----t------j----Q~o-p--t,aEvoXIMSTI"N~G'S~UruRF~AMCE~=-f-l 6~+'-7_5 ____ 1_+.,_o_o_""""---'-------'------=------'---1f----.....,-""2-+,_-;-o+-----'--....;;=-=;;;..,;;sE"'c"'n=DN;a,·c"°-""c---±---_--_--:mi-'-o----1 Tsa TO= 11.5' HOR.: 1"=20' Tsa ---- Tsa 1------,.------,------,------,-------r-------, 90 BUILDING ¥~LL -----.. "L 1----+----"-..._____,,__--+-_25_.9 __ _,_+-___ 4_4_.o-+---+--t-------l 80 B-1 B-2 ,-PRO OSED SURFACE -II 1--t---t..pc=c=wAnto-K-::-='----t-----7iC-__ RiBi~l~B~Offl)~-u-'4m,R~--------i-?--+---------i 70 l--+--+----+----+Qon,,_ ___ -+------+----+---+--------1 1---+---'--,,-+-----=-=--= ..... ------'=--==-a=-"-'-------' 65 ~w ----4+oo 4+5o TD=11.5' Tsa VERT.: 1"=10' B-4 Qppf Qop Tsa ____________ _,,__ ___ _ Approximate Boring Location Quaternary Previously Placed Fill Quaternary Old Paralic Deposits Tertiary Santiago Fonnation Approximate Geologic Contad Queried Where Uncertain C ~ngln•OMII Construction Testing & Engineering, Inc. l,@ 1"-, I c!;:~ -1~1.--1.._a~~10.0..-,.1~ GEOLOGIC CROSS SECTION PROPOSED TOYOTA CARISBAD SALES BUILDING 5434 PASEO DEL NORTE I 'io-15029G I VARIES CARLSBAD CALIFORNIA .., § LEGEND Alluvial Flood-Plain Deposits Old Paralic Deposits, Units 2-4 ~1-------------------------------------r---------------------------............. ----1 I C~ I:.~;;:::~ Construction Testing & Engineering, Inc. GE0~2~ ~ ~~~IN~007) _ ~ ~~~~'::v lnspedioo I T&Smg I~ I Enwonmental&Constn.w::tionEngneering I CM Engineering I Surve~ 54-34-PASIO DEL NORTE ~ CARJmlAD, CALIFORNIA .;;.,_ ___________________________________ ... _____________________________ ._ ___ . APPENDIX A REFERENCES Universal Engineering Services, 2023, Grading Plans for Toyota of Carlsbad, 5424 Paseo Del Norte, Carlsbad, CA 92008. dated March 14. Construction Testing and Engineering, Inc., 2021a, Response to: The City of Carlsbad 1st Review for CDP 2020-0024 (DEV2020-0130), Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California, Job No. 10-15029G, dated January 19. Construction Testing and Engineering, Inc., 2021 b, Additional Percolation Testing and Limited Infiltration Evaluation. Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California. Job No. 10-15029G, dated March 8. Construction Testing and Engineering, Inc.• 2020, Response to: The City of Carlsbad 1st Review for CDP 2020-0024 (DEV2020-0130), Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California, Job No. 10-15029G, dated January 19. (Attached) Construction Testing and Engineering, Inc.• 2019, Geotechnical Investigation, Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California, Job No. 10-15029G, dated August 2. ATTACHMENT 1 Response to Third Party Geotechnical Review Ninyo & Moore Project No. 109343017, Dated May 4, 2023 May 4, 2023 Project No. 109343017 Ms. Jessica Nishiura Hunsaker & Associates 9707 Waples Street San Diego, California 92121 Subject: Third-Party Geotechnical Review Proposed Sales Building at Toyota Carlsbad 5434 Paseo Del Norte Carlsbad, California 92008 Dear Ms. Nishiura: At your request, we have prepared this letter providing our review comments to the referenced geotechntcal reports prepared by Construction Testing & Engineering, Inc. (CTE) dated August 2, 2019 and March 8, 2021. Our comments regarding the geotechnical report include the following. Comment 1: The Geotechnical Consultant should review the project grading and foundation plans and provide any additional geotechnical recommendations as appropriate, and indicate if the plans have been prepared in accordance with the geotechnical recommendations provided in the referenced geotechnical reports (CTE, 2019, 2021b). Comment 2: The CTE report dated January 30, 2020 was referenced in the CTE letter dated March 8, 2019, but was not included in the review package We request that a copy of the CTE report dated January 30, 2020 be provided for us to review Comment 3: Per the City of Carlsbad (1993) guidelines, the Geotechnical Consultant should provide a geotechnical cross-section of the site. Additionally, an updated geotechnical map/plot plan showing the location of the cross-section should be provided. Comment 4: Per the City of Carlsbad (1993) guidelines, the Geotechnical Consultant should provide a geologic map. Comment 5: The Geotechnical Consultant should show the lateral limits of the recommended remedial grading on the geologic/geotechnical map. Specifically, with regards to impacts to existing improvements/structures. Comment 6: The referenced geotechnical report (CTE, 2019) utilizes the standards provided by the 2016 California Building Code (CBC) and American Society of Civil Engineers (ASCE) 7-10. As the standards of the 2022 CBC and ASCE 7-1 6 are the currently accepted practices, the Geotechnical Consultant should update the report and applicable sections utilizing those standards. 5710 Ruffin Road I San Diego, California 92123 1 p. 858.576.1000 I www.ninyoandmoore.com REFERENCES American Society of Civil Engineers (ASCE), 2017, Minimum Design Loads for Buildings and Other Structures, ASCE 7-16. California Building Standards Commission, 2022, California Building Code: California Code of Regulations, Title 24, Part 2, Volumes 1 and 2. City of Carlsbad, 1993, Technical Guidelines For Geotechnical Reports: dated January. City of Carlsbad, 2023, BMP Design Manual: dated January 11. Construction Testing and Engineering, Inc., 2019, Geotechnical Investigation, Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California, Job No. 10- 15029G, dated August 2. Construction Testing and Engineering, Inc., 2020, Response to: The City of Carlsbad 1st Review for CDP 2020-0024 (DEV2020-0130), Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California, Job No. 10-15029G, dated January 19. Construction Testing and Engmeenng, Inc., 2021a, Response to: The City of Carlsbad 1st Review for CDP 2020-0024 (DEV2020-0130), Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California, Job No. 10-15029G, dated January 19 Construction Testing and Engineering, Inc., 2021 b, Additional Percolation Testing and Limited Infiltration Evaluation, Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California, Job No. 10-15029G, dated March 8. Universal Engineering Services, 2023, Grading Plans for Toyota of Carlsbad, 5424 Paseo Del Norte, Carlsbad, CA 92008. dated March 14. Ninyo & Moore 15434 Paseo Del Norte. Carlsbad. California I109343017 I May 4 2023 1 ATTACHMENT 2 Update to Geotechnical Investigation, Proposed Sales Building at Toyota Carlsbad, 5434 Paseo Del Norte, Carlsbad, California, CTE Job No. 10-15029G, Dated January 30, 2020.