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HomeMy WebLinkAboutCUP 2017-0002; LA COSTA TOWN SQUARE LOT 5; FINAL SOILS REPORT; 2020-02-27 Prepared For: Mr. Scott Grady TRC Retail 4695 MacArthur Court, Suite 700 Newport Beach, CA 92660 FINAL AS-GRADED GEOTECHNICAL REPORT LA COSTA TOWN SQUARE LOT 5 Carlsbad, California A .. • A~ ____,.( I L ,~ I I \\I I I l \ I I \ I I 11 + February 27, 2020 SCST No. 180279N Report No. 6 Mr. Scott Grady TRC Retail 4695 MacArthur Court, Suite 700 Newport Beach, California 92660 Subject: FINAL AS-GRADED GEOTECHNICAL REPORT LA COSTA TOWN SQUARE LOT 5 3439 VIA MONTEBELLO CARLSBAD, CALIFORNIA 92009 Dear Mr. Grady: This report summarizes the results of the geotechnical observation and testing services that SCST, LLC (SCST), an Atlas company, performed during earthwork construction for the building pad and site improvements at the subject project. In our opinion, the soil engineering and engineering geologic aspects of the grading are in compliance with the approved geotechnical report and the grading plan, Drawing No. 512-8A (referenced). If you have any questions, please call us at (619) 280-4321. Respectfully submitted, SCST, LLC Isaac Chun, GE 2649 Thomas “Higgy” Higginbotham Principal Engineer Project Manager PFL:ds Distribution: Addressee via e-mail at sgrady@trcretail.com A•• A~ _____,., I L ) 1 o .___ ~c s ii SCST, LLC Corporale Headquarlers + 6280 Riverdale Street + San Diego, CA 92120 T 877.215.4321 + P 619.280.4321 + r: 619.280.4717 + w www.scst.com TABLE OF CONTENTS SECTION PAGE i 1. INTRODUCTION ..................................................................................................................... 1 2. SCOPE OF WORK ................................................................................................................. 1 3. SITE DESCRIPTION ............................................................................................................... 1 4. PROJECT DESCRIPTION ...................................................................................................... 1 5. SITE PREPARATION AND GRADING .................................................................................. 1 6. AS-GRADED GEOLOGIC CONDITIONS .............................................................................. 2 7. FIELD OBSERVATIONS AND TESTING ............................................................................... 2 8. RETAINING WALLS ............................................................................................................... 2 9. SITE IMPROVEMENTS .......................................................................................................... 3 10. FOUNDATIONS ...................................................................................................................... 3 11. CONCLUSIONS ...................................................................................................................... 3 12. LIMITATIONS ......................................................................................................................... 3 13. REFERENCES ........................................................................................................................ 4 ATTACHMENTS TABLES Table 1 .................................................................................................... Compaction Test Results Table 2 ...................................................................................................... Laboratory Test Results FIGURES Figure 1 .............................................................................................................. Site Location Map Figure 2 ............................................................................................ As-Graded Geotechnical Map 1 1. INTRODUCTION SCST, LLC (SCST), an Atlas company, is pleased to present the results of our geotechnical observation and testing services provided during earthwork construction for the proposed La Costa Town Square project between December 4, 2018 and October 15, 2019. The purpose of our work was to observe the geotechnical conditions exposed during grading and evaluate conformance of the geotechnical aspects of earthwork construction with the project plans and geotechnical recommendations. 2. SCOPE OF WORK SCST provided observation and compaction testing services during earthwork construction to prepare the building pad and site improvements for the subject development in accordance with the recommendations of the referenced geotechnical report. To support the field testing, representative samples of the material used for fill and backfill were tested in our laboratory. Field dailies were prepared at the end of each day summarizing our observations and testing. Our services did not include supervision or direction of the actual work performed by the contractors. 3. SITE DESCRIPTION The rectangular-shaped site is located at Lot 5 in La Costa Town Square complex in Carlsbad, California. Figure 1 presents a site location map. The site is bordered by Rancho Santa Fe Road on the north, Via Campanile on the east, Via Mercato on the south, and other commercial buildings on the west. Prior to construction, the site elevations ranged from about 333 to 340 feet above mean sea level (MSL). After grading, site elevations ranged from about 333 to 334 feet. 4. PROJECT DESCRIPTION The project consists of constructing a multiplex cinema with a finish floor elevation of about 334 feet above mean sea level. A gravity retaining wall was constructed along the northeastern side of the project site. 5. SITE PREPARATION AND GRADING Site preparation began with the removal of existing improvements, vegetation, and debris. Prior to grading, the site was underlain Delmar Formation and previously placed engineered fill by SCST. Grading consisted of excavating the formational material or shallow fill to provide a minimum of 2 feet of compacted fill below the building foundations. Areas of deepened foundations at the east portion of the building were overexcavated to expose competent formational materials. Compacted fill was then placed to provide a compacted fill mat beneath the proposed footings. The grading contractor scarified, moisture conditioned, and compacted the surface exposed at the bottom of all excavations. The excavated material was screened for reuse as compacted fill, 2 La Costa Town Square Lot 5 Carlsbad, California SCST Project No. 180279N-06 TRC Retail February 27, 2020 and the oversized material and debris were hauled from the site. Fill was moisture conditioned and compacted until planned elevations were reached. Compaction was achieved by means of a front-end loader and dozer. This process continued until planned elevations were reached. 6. AS-GRADED GEOLOGIC CONDITIONS In our opinion, the geologic conditions observed at the site were generally as anticipated to those described in the project geotechnical report (SCST 2018). As observed during grading, the site is underlain by compacted artificial fill and Delmar Formation. The as-graded geologic conditions are depicted on Figure 2. Descriptions of the materials are presented below. Fill (Qaf): Compacted artificial fill derived from on-site materials consisting of silty to clayey sand with varying amounts of gravel and cobbles was placed during grading. The fill overlies Delmar Formation. Delmar Formation (Td): The Delmar Formation underlies the fill. In general, the Delmar Formation consists of weakly indurated, sandy claystone and weakly cemented, clayey sandstone with trace gravel. Trace cobble and layers of well-formed gypsum crystals were also encountered in some of the borings. Groundwater: Groundwater was not observed during grading. Future site irrigation may alter the groundwater conditions, resulting in unpredictable perched water and seepage. Groundwater conditions may also change in the future due to broken pipes or rainfall. 7. FIELD OBSERVATIONS AND TESTING A representative of SCST performed periodic field observations and compaction tests during the site improvement operations. Field density (compaction) tests were performed in accordance with ASTM D6938 (nuclear gauge). Table 1 presents the compaction test results, and Figure 2 presents the approximate compaction test locations. Maximum dry density and optimum moisture content tests were performed on soil samples in accordance with ASTM D1557. The results of these tests were used in conjunction with the field density tests to determine the degree of relative compaction of the materials. The laboratory test results are presented in Table 2. 8. RETAINING WALLS We performed observation and testing of the backfill soils and observed the installed wall drainage system outlets. The wall backfill was placed in thin lifts, moisture conditioned to near optimum moisture content, and compacted until field density tests indicated a minimum of 90% relative compaction. Compaction was achieved by a backhoe with a sheepsfoot roller. The backfill was moisture conditioned to near optimum moisture content and compacted until field density tests ____,.~TS--._ '1 ii _ .............. _ ---------+ 3 La Costa Town Square Lot 5 Carlsbad, California SCST Project No. 180279N-06 TRC Retail February 27, 2020 indicated a minimum of 90% relative compaction. Figure 2 presents the approximate compaction test locations. 9. SITE IMPROVEMENTS Site improvements consist of utility trench backfill, sidewalk, and pavements. Utility trench backfill was observed on a periodic basis to be placed in relatively thin lifts, moisture conditioned to near optimum moisture content, and compacted until field density tests indicated a minimum of 90% relative compaction. The upper 8 inches of subgrade soils beneath curb and gutter, and pavements were scarified, moisture conditioned to near optimum moisture content, and compacted until field density tests indicated a minimum of 95% relative compaction. Aggregate base was placed over the prepared subgrade and compacted using vibratory steel-drum rollers. Asphalt concrete was placed over the compacted base course using conventional paving equipment, then compacted with steel drum rollers. Figure 2 presents the approximate compaction test locations of site improvements. 10. FOUNDATIONS We observed foundation excavations to evaluate conformance with the project geotechnical recommendations. The foundations consist of continuous and spread footings. The foundations were excavated to the minimum recommended depth and reached suitable bearing materials consisting of compacted fill. The fill soils generally consist of silty to clayey sand. 11. CONCLUSIONS In our opinion, the soil engineering and engineering geologic aspects of the grading are in compliance with the approved geotechnical report and the grading plan, Drawing No. 512-8A. The conclusions contained herein are based on our geotechnical observation and compaction testing services performed between the dates indicated. In general, our observations confirm that the subsurface conditions and bearing materials are in substantial conformance with the project geotechnical report. The bearing materials are considered suitable for support of the structure. No representations are made to the quality and extent of materials not observed or materials not in conformance with the project specifications or our geotechnical recommendations. 12. LIMITATIONS This report covers only the services that SCST performed between the dates indicated. Our opinions are based on our observations and the relative compaction test results and are limited by the scope of the work that we agreed to perform. As used herein, the term "observation" implies only that we observed the progress of work for which we were involved. We performed field density tests, which, in conjunction with our ~ + ~ii-------------- 4 La Costa Town Square Lot 5 Carlsbad, California SCST Project No. 180279N-06 TRC Retail February 27, 2020 observations, were the basis for our opinion as to whether the work was performed in substantial conformance with the project documents. Horizontal and vertical control was provided by the contractor. The accuracy of the grading limits and elevations are based on work by others. The accuracy of the test locations and elevations is a function of the accuracy of the topographic and lateral control provided by others. Their locations and elevations were determined by pacing and hand level methods and should be considered accurate only to the degree implied by the method used. Our work was performed in accordance with the currently accepted standard of practice, and in such a manner as to provide a reasonable measure of the compliance of the grading and backfill operations with the project requirements. No warranty, express or implied, is made or intended with respect to the work that we have performed, and neither the performance of this work nor the submittal of this report should be construed as relieving the contractor of their responsibility to conform with the project requirements. Our work was generally performed on an “on-call” basis. Therefore, the in-place density tests performed by our field representative can only be construed as representative of the areas tested as shown on the attached figures. 13. REFERENCES Excel Engineering (2018), Grading Plans, La Costa Town Square Building 5, GR2018-0025, Amend 2017-0003, Carlsbad, California, Project No. CUP2017-0002, dated October 11. SCST, Inc. (2018), Geotechnical Investigation, La Costa Town Square Lot 5, Rancho Santa Fe Road and La Costa Avenue, Carlsbad, California, SCST No. 180279N, dated September 17. SCST, LLC (2019), Interim As-Graded Report, La Costa Town Square Lot 5, Rancho Santa Fe Road and La Costa Avenue, Carlsbad, California, SCST No. 180279N-5R, dated March 6. ~ + ~ii-------------- Table 1 - Compaction Test ResultsClient:Project:Test Method: ASTM D 6938ASTM D693 / D2950Rancho Santa Fe Road & La Costa AvenueCarlsbad, CaliforniaTest #Test DateTest TypeTest LocationElevation (feet)Proctor IDMoisture Content (%)In-Place Density (pcf)Relative CompactionSpecified CompactionPass/Fail1 12/4/2018Grading Theater Building pad331 #2 17.8 113.0 92%90% PASS2 12/4/2018Grading Theater Building pad 331 #3 11.4 116.1 92%90% PASS3 12/4/2018Grading Theater Building pad 332.5 #3 10.9 122.7 97%90% PASS4 12/5/2018Grading Theater Building pad 332 #1 10.6 123.1 98%90% PASS5 12/5/2018Grading Theater Building pad 333 #2 13.1 112.2 92%90% PASS6 12/10/2018Grading Theater Building pad 333 #2 13.1 116.2 95%90% PASS7 12/10/2018Grading Theater Building pad 332 #2 12.7 117.2 96%90% PASS8 12/10/2018Grading Theater Building pad 331 #2 13.1 111.2 91%90% PASS9 12/11/2018Grading Theater Building pad (Retest of #1)332 #2 13.0 116.9 95%90% PASS10 12/11/2018Grading Theater Building333 #3 11.1 114.3 91%90% PASS11 12/12/2018Grading Theater Building333 #3 11.6 121.0 96%90% PASS12 12/12/2018Grading Theater Building332.5 #1 12.2 119.1 94%90% PASS13 12/12/2018Grading Theater Building333 #3 13.4 116.5 92%90% PASS14 12/13/2018Grading Theater Building333 #2 12.3 110.4 90%90% PASS15 12/26/2018 Storm Drain 12" HDPE, Southeast Corner of project330 #2 12.8 111.7 91%90% PASS16 12/26/2018 Storm Drain 12" HDPE, Southeast Corner of project330 #2 13.2 112.6 92%90% PASS17 12/26/2018 Storm Drain 12" HDPE, Southeast Corner of project332 #2 13.0 112.9 92%90% PASS18 1/11/2019Grading North end building deepened footing over excavation324 #4 18.4 104.5 87%90%FAIL19 1/11/2019Grading South end building deepened footing over excavation324 #4 16.0 109.7 92%90% PASS20 1/11/2019Grading Middle of building deepened footing over excavation325 #4 15.2 108.3 91%90% PASS21 1/11/2019Grading North end building deepened footing of the over excavation326 #4 15.5 107.4 90%90% PASS22 1/14/2019Grading North end building deepened footing of the over excavation328 #4 11.0 102.7 86%90%FAIL23 1/14/2019Grading North end building deepened footing & CMU Fill (Retest of #22)328 #4 16.1 108.2 90%90% PASS24 1/14/2019Grading Middle Zone of building deepened footing & CMU Fill329 #4 11.1 114.9 96%90% PASS25 1/14/2019Grading North end building deepened footing & CMU Fill330 #4 12.3 115.6 97%90% PASS26 1/14/2019Grading Center building deepened footing & CMU Fill332 #4 11.9 114.5 96%90% PASS27 1/14/2019Grading Southeasterly side building deepened footing & CMU Fill333 #4 12.6 115.8 97%90% PASS28 1/14/2019Grading North middle of building deepened footing & CMU Fill (Retest of #18) 324 #4 12.9 114.5 96%90% PASS29 1/14/2019Grading Gas Line removal and overexcavated Fill330 #2 14.4 110.1 90%90% PASS30 1/14/2019Grading Gas Line removal and overexcavated Fill332 #2 14.7 111.4 91%90% PASS31 1/22/2019Grading Northwest end of Building333.7 #5 11.1 123.9 90%90% PASS32 1/22/2019Grading East side Middle of Building333.7 #3 13.4 119 94%90% PASS33 1/22/2019Grading Northwest side of Building333.7 #2 14.6 118.4 97%90% PASS34 1/22/2019Grading Southwest side of Building333.7 #2 13.3 118.5 97%90% PASS35 1/30/2019Sewer6” private sewer south side parking lot327 #4 16.2 107.4 90%90% PASS36 1/30/2019Sewer6” private sewer south side parking lot329 #4 16.7 107.7 90%90% PASS37 1/31/2019Sewer6” private sewer southeast end projects driveway327 #4 15.6 114.5 96%90% PASS38 1/31/2019Sewer6” private sewer southeast end projects driveway327 #4 16.3 115.8 97%90% PASS39 1/31/2019Sewer6” private sewer south end projects parking lot330 #4 17.0 107.8 90%90% PASS40 1/31/2019Sewer6” private sewer south end projects parking lot332 #4 16.3 109.3 91%90% PASS41 12/4/2018SewerTheater Building pad330 #4 12.7 112.2 94%90% PASS42 12/4/2018SewerTheater Building pad 330 #4 16.4 116.8 98%90% PASS43 12/4/2018SewerTheater Building pad 327 #4 17.1 102.6 86%90%FAILSCST LCC - San DiegoLEA: 47, Exp: 04/25/20216280 Riverdale StreetSan Diego, Ca 92120Phone: (619 ) 280-4321 / Fax: (619) 280-4717La Costa Town Square Lot 5San Diego, California La Costa Town Square 5550 Carmel Mountain Road, Suite 204TABLE 1Ill -- Table 1 - Compaction Test ResultsClient:Project:Test Method: ASTM D 6938La Costa Town Square ASTM D693 / D2950Rancho Santa Fe Road & La Costa AvenueCarlsbad, CaliforniaTest #Test DateTest Type Test LocationElevation (feet)Proctor IDMoisture Content (%)In-Place Density (pcf)Relative CompactionSpecified CompactionPass/Fail44 12/5/2018SewerTheater Building pad (Retest of #43)327 #4 17.0 109.1 91%90% PASS45 12/5/2018SewerTheater Building pad 328 #4 17.2 107.8 90%90% PASS46 12/10/2018SewerTheater Building pad 329 #4 15.8 108.5 91%90% PASS47 12/10/2018SewerTheater Building pad 330 #4 17.2 109.5 92%90% PASS48 12/10/2018SewerTheater Building pad 331 #4 16.6 108.6 91%90% PASS49 12/11/2018SewerTheater Building pad332 #4 16.8 107.7 90%90% PASS50 12/11/2018SewerTheater Building pad332 #4 16.6 108.6 91%90% PASS51 7/25/2019BaseEast footing for pedestrian bridge330 B-1 11.8 117.8 96%95% PASS52 7/25/2019BaseWest footing for pedestrian bridge330 B-1 12.1 118.1 96%95% PASS53 9/16/2019 Subgrade: Curb and Gutter Front of Theater Building333 #5 7.1 124.7 91%90% PASS54 9/16/2019 Subgrade: Curb and Gutter Southwest corner of Theater Building333 #5 6.6 126.8 92%90% PASS55 9/16/2019 Subgrade: Curb and Gutter Northwest corner of Theather Building333 #5 6.5 125.7 91%90% PASS56 9/16/2019 Subgrade: Curb and Gutter West side of Theater Building333 #5 7.4 126.8 92%90% PASS57 9/24/2019 Subgrade: Curb and Gutter South of Theater Building333 #5 6.6 124.5 91%90% PASS58 9/24/2019 Subgrade: Curb and Gutter South of Theater Building333 #5 7.4 124.6 91%90% PASS59 9/26/2019 Subgrade: Sidewalk Southwest corner of Theater Building333.5 #5 6.6 124.7 91%90% PASS60 9/26/2019 Subgrade: Sidewalk South side of Theater Building333.5 #5 7.8 123.7 90%90% PASS61 10/4/2019 Base: Sidewalk South side of Theater Building333.5 B-1 10.7 119.5 97%95% PASS62 10/4/2019 Subgrade: Pavement South side of Theater Building333 #5 4.9 132.4 96%95% PASS63 10/4/2019 Subgrade: Pavement South side of Theater Building333 #5 5.1 130.8 95%95% PASS64 10/4/2019 Subgrade: Pavement West side of Theater Building333 #5 5.3 131.0 95%95% PASS65 10/8/2019 Base: Sidewalk South side of Theater Building333.5 B-1 9.4 118.2 96%90% PASS66 10/8/2019 Base: Sidewalk South side of Theater Building333.5 B-1 11.5 119.2 97%90% PASS67 10/9/2019 Subgrade: Curb and Gutter Driveway on the northwest side of Theater Building332 #3 8.9 124.0 98%90% PASS68 10/9/2019 Subgrade: Curb and Gutter Alley on north side of Theater Building333 #4 12.9 113.7 95%95% PASS69 10/9/2019 Subgrade: Curb and Gutter Alley on north side of Theater Building333.5 #4 19.7 115.8 97%95% PASS70 10/9/2019 Subgrade: Pavement Alley on north side of Theater Building333 #1 12.3 122.5 97%95% PASS71 10/11/2019 Base: Roadway South Parking on west side of Theater Building AB B-1 12.9 118.2 96%95% PASS72 10/11/2019 Base: Roadway Drive north of ribbon gutter on north side of Theater BuildingAB B-1 12.2 118.4 96%95% PASS73 10/11/2019 Base: Roadway Drive south of ribbon gutter on north side of Theater BuildingAB B-1 13.1 117.9 96%95% PASS74 10/11/2019 Base: Roadway Drive northwest corner on north side of Theater BuildingAB B-1 11.1 119.8 97%95% PASS75 10/11/2019 Base: Roadway Drive lane on west side of Theater Building AB B-1 11.7 120.1 98%95% PASS76 10/11/2019 Base: Roadway North parking are on west side of Theater BuildingAB B-1 11.9 119.4 97%95% PASS77 10/11/2019 Base: Roadway South drive lane on west side of Theater BuildingAB B-1 11.9 118.2 96%95% PASS78 10/11/2019 Base: Roadway Drive Lane on southwest side of Theater BuildingAB B-1 13.1 118.9 97%95% PASS79 10/11/2019 Base: Roadway Drive lane on south side of Theater BuildingAB B-1 13.3 119.3 97%95% PASS80 10/11/2019 Base: Roadway Drive lane on south side of Theater BuildingAB B-1 12.4 118.0 96%95% PASSAC1 10/15/2019 Asphalt Wear Course Parking area on north side of Theater BuildingAC AC-1 - 141.4 98%95% PASSAC2 10/15/2019 Asphalt Wear Course Parking area on south side of trash enclosureAC AC-1 - 139.8 97%95% PASSAC3 10/15/2019 Asphalt Wear Course Parking area on east side of Theater BuildingAC AC-1 - 141.1 98%95% PASSAC4 10/15/2019 Asphalt Wear Course Parking area, southeast of Theater BuildingAC AC-1 - 140.4 98%95% PASSAC5 10/15/2019 Asphalt Wear Course Driveway on south side of Theater BuildingAC AC-1 - 141.2 98%95% PASSAC6 10/15/2019 Asphalt Wear Course Driveway on south side of Theater BuildingAC AC-1 - 139.8 97%95% PASSLa Costa Town Square Lot 55550 Carmel Mountain Road, Suite 204SCST LCC - San DiegoLEA: 47, Exp: 04/25/20216280 Riverdale StreetSan Diego, Ca 92120Phone: (619 ) 280-4321 / Fax: (619) 280-4717San Diego, California TABLE 1~Cl --:~g Table 2 - Laboratory Test ResultsClient:Project:La Costa Town Square Lot 5La Costa Town Square 5550 Carmel Mountain Road, Suite 204Rancho Santa Fe Road & La Costa AvenueCarlsbad, CaliforniaOptimum Moisture (%)8.611.29.512.27.411.3Gray Recycled Aggregate BaseSan Diego, California #4 (36814)119.6Light Brown SILTY SAND (SM)122.9SCST LLC - San DiegoLEA: 47, Exp: 04/25/20216280 Riverdale StreetSan Diego, Ca 92120Phone: (619 ) 280-4321 / Fax: (619) 280-4717Maximum Density and Optimum Moisture Summary (ASTM D1557)Test # Soil Description#5 (36815) Brown SILTY CLAY with GRAVEL (SC)137.5Maximum Density, pcf#3 (35794) Brown SILTY SAND with GRAVEL (SM)126.0#1 (35792) Light Brown SILTY SAND with GRAVEL (SM)126.1#2 (35793) Light Brown SILTY SAND (SM)122.5B-1 (47411)AC1 (48945)1/2" Type III C3 PG 64-10 Theater Parking Lot143.9Hveem - Maximum Bulk Specific Gravity (Cal 308)Test #Material Description Sample Location / Representative Area Unit Weight, pcfTABLE 2~~ -:~g I I PROJECT SITE©2020 OpenStreet Map1SITE VICINITY MAPLa Costa Town Square Lot 5Carlsbad, CaliforniaDate:Job No.:By:February 2020180279N-6DTC/ACFFigure:SCALE (feet)N7501,5000PROJECTSITEKEY MAPJ \ \. \ \j %H ~,~ao<eS<c~, L 1 ·-------------------------·-·: \ \ ~ g\ ~ F A-■ Ar!! La Casta Heights Elementary School Location of In-Place DensityTestSCST LEGEND:2AS-GRADED GEOTECHNICAL MAPLa Costa Town Square Lot 5Carlsbad, CaliforniaDate:Job No.:By:February 2020180279N-6DTC/ACFFigure:SCALE (feet)NOTE: All locations are approximateN501000Basemap: Excel Engineering, La Costa Town Square - Building 5 Grading Plan, Drawing No. 512-8A, Sheet 8 (October, 2018)14121329302522, 23281821242026192712433171163410339532815171647484943, 444645504536424137393840Geologic ContactDelmar Formation, Buried byCompacted FillPreviously Documented Fill,Buried by Compacted FillLimits of GradingTdTdTdQafLocation of Asphalt In-PlaceDensity Test63616260647877AC6757679AC2686774738072AC1AC4AC57170AC369656659575856555453525180AC6TdQafOT 4 /5998 r I t • I • • /1 --s LOT 5 A/AP 15998 • • • 0 0