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Home My WebLink AboutPD 2022-0007; HAGUE RESIDENCE; SOILS REPORT-RESPONSE TO COMMENTS; 2022-06-10 Date: June 10th, 2022 To: Ms. Nichole Fine City of Carlsbad Land Development Engineering 1635 Faraday Avenue Carlsbad, California 92008-7314 Re: Proposed new, single-family residence, to be constructed at Cynthia Lane (APN:156-231- 70), Carlsbad, California Subject: Response to Comments. EDG Project: 216614-1 References: 1. “Preliminary Geotechnical Investigation and Recommendations Proposed, New Single-Family Residence to be located at Cynthia Lane (APN:156-231-70), Carlsbad, California”, prepared by Engineering Design Group, dated October 18th, 2021. 2. Addendum No. 1 – Updated Recommendations and Figures, prepared by Engineering Design Group, dated June 2nd, 2022. 3. Third-Party Geotechnical Review (First) – Cynthia Lane SFR – Carlsbad, California – APN: 145- 231-70 – GR2022-0011, by Hetherington Engineering, Inc., Project No. 9671.1, Log No. 21849, dated April 19, 2022. 4. Engineering Design Group, Grading Plan for Hague Residence– APN: 260-213-13, dated June 2nd, 2022. Please find below our responses to geotechnical review comments (Ref. No. 3) to our original report (Ref. No. 1). Comment No. 1 Please see Addendum No. 1 - Grading and Earthwork section. Comment No. 2 Please see updated Geotechnical Map and Cross-Section, attached herein. Comment No. 3 Please see Addendum No. 1 – Site and Project Description section. ENGINEERING DESIGN GROUP www.designgroupca.com 2121 Montiel Road, San Marcos, CA 92069 760.839.7302 Comment No. 4 Provided additional specific language to specific laboratory tests run as part of our field investigation. Please see Addendum No. 1 – Field and Subsurface Investigation section. Comment No. 5 Please see Addendum No. 1 – Geologic Setting section. Comment No. 6 Additional expansion index tests were conducted to demonstrate that soils are not anticipated to be expansive. Conclusions and recommendations are provided based upon our visual observation of the soils conditions within our test pits, the testing that was conducted (including corrosivity and EI), and our extensive experience with the encountered soil materials in the area, the conditions of the site and in consideration of the proposed nature of the single family residence. In our opinion additional testing is not necessary to provide specific recommendations for the proposed residence. Comment No. 7 Our review of seismic design criteria provided in our original report was consistent with Site Class D, as described in our original report. Please provide reference for comment, such that we can try to better address it. Comment No. 8 Please see Addendum No. 1 – Grading and Earthworks section. Comment No. 9 Expansive index test was conducted to demonstrate expansion potential is in the very low range. Comment No. 10 Please see Addendum No. 1 – Foundation Settlement section. If you have any questions with respect to these comments, please don’t hesitate to contact us. Sincerely, ENGINEERING DESIGN GROUP Erin E. Rist California RCE #65122 EDG Project No. 216614-1 Date: June 10th, 2022 To: Ms. Nichole Fine City of Carlsbad Land Development Engineering 1635 Faraday Avenue Carlsbad, California 92008-7314 Re: Proposed new, single-family residence, to be constructed at Cynthia Lane (APN:156-231- 70), Carlsbad, California Subject: Addendum No. 1 – Updated Recommendations and Response to Comments. EDG Project: 216614-1 References: 1. “Preliminary Geotechnical Investigation and Recommendations Proposed, New Single-Family Residence to be located at Cynthia Lane (APN:156-231-70), Carlsbad, California”, prepared by Engineering Design Group, dated October 18th, 2021. 2. Third-Party Geotechnical Review (First) – Cynthia Lane SFR – Carlsbad, California – APN: 145- 231-70 – GR2022-0011, by Hetherington Engineering, Inc., dated April 19, 2022. 3. Engineering Design Group, Grading Plan for Hague Residence– APN: 260-213-13, dated June 2nd, 2022. 1.0 PURPOSE We have prepared this addendum to provide updated recommendations to the above referenced preliminary geotechnical report (Reference No. 1) based upon the updated preliminary grading plans (Reference No. 3), for the proposed new, single-family residence, to be located at Cynthia Lane (APN: 156- 231-70), in the City of Carlsbad. This addendum will also address City of Carlsbad – Land Development Engineering Department’s – Third-Party Geotechnical Review comments (Reference No. 2). 2.0 SITE AND PROJECT DESCRIPTION The subject property is located at Cynthia Lane (156-231-70), in the City of Carlsbad, California. The subject lot is mostly undeveloped, except for a shed, and is covered with low-lying vegetation and sporadic trees. The subject lot is bordered by single-family homes to the north, south and east, and borders Cynthia Lane to the west. The proposed development generally remains the same as the one stated in our original report and consists of the construction of a new single-family residence, and associated hardscape/landscape improvements. ENGINEERING DESIGN GROUP www.designgroupca.com 2121 Montiel Road, San Marcos, CA 92069 760.839.7302 EDG Project No. 216614-1 Based upon our review of the grading plan, site grading will generally consist of increasing the size of the building pad area to accommodate proposed new single-family residence. The construction of a retaining wall along the western property line and a general fill in the area of new improvements is anticipated. 3.0 FIELD AND SUBSURFACE INVESTIGATION As described in our original report, our field investigation consisted of site reconnaissance, site field measurements, observation of existing conditions on-site and on adjacent sites and a limited subsurface investigation of soil conditions. No additional subsurface investigation was performed for this addendum. Our original subsurface investigation consisted of the excavation of two exploratory test pits / hand auger borings, the visual observation and logging of soil types encountered, and the sampling of soil profiles for laboratory testing. Laboratory testing were performed on selected soil samples obtained during our investigation and included expansion potential, sulfate content/corrosivity. The data from our original investigation, as well as our experience with soil types and soil conditions in the general area, was utilized to inform the recommendations in our original report and this addendum. As described in our original report, our experience with projects underlain by paralic deposits, do not require specific/additional reinforcement or specialty detailing to address expansive soils. Additional laboratory testing of onsite samples to determine expansion potential of soil profiles, indicates onsite profiles tested, have a very low potential for expansion. 4.0 GEOLOGIC SETTING The project site is located within the Peninsular Ranges Geomorphic Province of California. The Peninsular Ranges extend 125 miles from the Transverse Ranges and the Los Angeles Basin south to the Mexican Border and beyond. This Geomorphic province is bounded on the east by the Colorado Desert and the Gulf of California. The topography of the area in and around the subject site consists of coastal foothill terrain and relatively shallow drainages. The project site is overlain by weathered profiles underlain by late to middle Pleistocene-era paralic deposits (as mapped per Kennedy, et.al., 2007). 5.0 GRADING AND EARTHWORK Based upon our review of the current grading plan (Reference No. 3), we anticipate the construction of a new, single-family residence with associated hardscape and landscape improvements. Proposed residence is anticipated to be constructed using shallow foundations and slab-on-grade floors. Based upon our review of the updated grading plans (Reference No. 3), we find the plans are in general conformance with the above referenced geotechnical report (Reference No. 1) and this addendum. We anticipate grading operations will consist of the removal and re-compaction of the upper 3 feet of EDG Project No. 216614-1 material in the area of the proposed residence, retaining/landscape wall backfilling operations and fine grading for drainage and landscape purposes. New residence foundations and slab-on-grade floors are anticipated to be founded in competent re-compacted materials. 5.1 Removals In areas of new proposed structures, topsoil/fill/weathered profiles found to mantle the site, are not suitable for the structural support of buildings or structural improvements in their present state. In area of proposed residence. We anticipate grading will consist of the removal of all unsuitable topsoil/fill and weathered soil, at the upper 3 feet, to competent material, scarification of excavation subgrade, moisture conditioning, placement, and re-compaction of fill material per Appendix B of original report. New fills should be re-compacted to a minimum of 90 percent relative compaction (ASTM D1557 – latest edition). Removals should extend a minimum of 3 feet horizontally (or to a distance at least equal to the depth of the fill) beyond the footprint of the proposed structures (including any exterior columns) and settlement sensitive improvements. All backfill/fill material shall be tested for relative density every 2 vertical feet at a minimum. 5.2 Transitions All settlement sensitive improvements (including but not limited to building structures, site retaining walls, etc.), should be constructed on a uniform building pad. We anticipate all new footings and slab-on- grade floors for the proposed residence, will be founded in competent re-compacted material. No transitions or undercuts are anticipated. Based upon our review of the preliminary grading plans, we anticipate adjacent property and improvements will not be negatively impacted from a geotechnical standpoint, provided the recommendations of this report, generally accepted construction practices, applicable codes, OSHA requirements, civil design elements are implemented and applicable city and/or county standards are followed. 6.0 FOUNDATION SETTLEMENT Where the recommendations of our original report and this addendum are followed, the maximum expected total static settlement for the proposed structure supported on a conventional foundation system utilizing a maximum allowable soil bearing pressure of 2,000 psf (deriving support in competent re-compacted fill material), is estimated to be on the order of ½ to 1 inch. Differential settlement is not expected to exceed ½ inch over a distance of twenty (20) feet. All recommendations and design parameters from our original report, not discussed herein, remain applicable. If you have any questions regarding this letter, please feel free to contact our office. EDG Project No. 216614-1 Sincerely, ENGINEERING DESIGN GROUP Erin E. Rist RCE #65122 Steven Norris GE 2590; CEG 2263 Attachments: • Figure A – Geologic/Geotechnical Map • Figure B – Geologic/Geotechnical Section • Expansion Index Laboratory Test Result C 65122 0 ~of ESS lo,, < -"If( ~i~~ ~{s\ ~"" 2590 Exp. 12-31-23 \, ' 10-3988L Lab Number:33399 E.D.G.Date Sampled:4/29/2022 L.V.Date Tested:5/6/2022 LAB WORK SHEET EXPANSION INDEX TEST Initial Final WET WEIGHT (g)220.4 442.5 DRY WEIGHT (g)206.1 390.5 % MOISTURE (%)6.9 13.3 WEIGHT OF RING & SOIL (g)792.6 WEIGHT OF RING (g)364.6 WEIGHT OF SOIL (lbs.)0.9436 VOLUME OF RING (ft.3)0.0073 WET DENSITY (pcf)129.8 DRY DENSITY (pcf)121.3 % SATURATION (%)48.5 EXPANSION READING DATE TIME: INITIAL READING INCH 0.0205 VERY LOW 0-20 LOW 21-50 MEDIUM 51 -90 FINAL READING HIGH 91-130 0.0204 VERY HIGH 130> EXPANSION INDEX 0 NOTES: Equipment ID: 2B EI at saturation between 48-52% Measured EI:-0.1 Measured Saturation:48.5 EI at 48-52% Saturation:0 ASTM D 4829 TEST RESULTS Soil Description:Reddish Brown (S.M.) Job Name:E.D.G. (Hauge) (4814.1003988.0000) Job Number: Sampled By: Tested By: Soil Location:Not Submitted A Universal Engineering Sciences Company i i CYNTHIA LANE (APN:156-231-70)CARLSBAD, CALIFORNIA216614-15-9-2022FIGURE NO.:ENGINEERING DESIGN GROUP www.designgroupca.com PROPOSED FINISH FLOOR = 1 J0.25 HAGUE RESIDENCE GEOLOGIC/GEOTECHNICAL MAP ~--ti "" 7 ~ ----c ,... =--'.lE--;;;: :c 2121 Montiel Road, San Marcos, CA 92069 760.839.7302 LEGEND @;] ( ) T2 () A_I _!A + + + + + + + + + + + + + + + + + + + + JOB NAME: JOB ADDRESS: JOB NO.: DATE: Topsoil / Fill / Weathered Profiles (buried units shown in parentheses) Very Old Paralic Deposits (As Mapped per Kennedy, et.al. 2007) Exploratory Test Pit -Per Original Report Geologic Contact (In section view) Approximate Property Line Boundary Section Approximate Limits of Proposed Improvements. Residence to be Founded with Slab-On-Grade Floors. Limits of Remedial Grading Driveway and Hardscape Areas 1-Foot Removal and Re-Compaction Limits of Remedial Grading Residence and Garage Areas J-Foot Removal and Re-Compaction Approximate Limits of Remedial Grading (Cross -Section View) HAGUE RESIDENCE A CYNTHIA LANE (APN:156-231-70)CARLSBAD, CALIFORNIA216614-15-9-2022FIGURE NO.:140.0 138. 136. 134. 132. 130.0 128. 126. 124. 122. 120.0 118. 176. 115.0 o+o .00 PL I ROPOSED XISTING RETAINING WALL GRADE 0+00.00 0+25.00 0+50.00 ENGINEERING DESIGN GROUP www.designgroupca.com 2121 Montiel Road, San Marcos, CA 92069 760.839.7302 HAGUE RESIDENCE GEOLOGIC/GEOTECHNICAL SECTION APPROXIMATE LIMITS OF REMEDIAL GRADING 0+75.00 SECTION A -A' SCALE: 1 "= 1 O' 1+00.00 JOB NAME: JOB ADDRESS: JOB NO.: DATE: 1 +25.00 PL I POSED I DE HAGUE RESIDENCE 1+5. 1+50 B