Loading...
HomeMy WebLinkAboutCDP 2019-0002; SMITH (HILLSIDE DR) RESIDENCE; FINAL SOILS REPORT; 2022-04-15 15 April 2022 Mr. Jessie Smith Job No. 18-11842 447 Bougher Road San Marcos, CA 92068 Subject: Report of Rough Grading Observations and Soil Testing Smith Residence 4246 Hillside Drive Carlsbad, California Dear Mr. Smith: Per our work agreement and as required by the City of Carlsbad, Geotechnical Exploration, Inc. hereby presents this report of grading observations and soil testing for the work performed at the project site, refer to Vicinity Map (Figure No. I). The work reported herein was performed between June 22, 2021 and March 11, 2022. Our firm issued a Preliminary Geotechnical Investigation dated April 9, 2018, followed by an Update Report of Preliminary Geotechnical Investigation dated November 13, 2020 for the project site. We also issued the following documents: 1.) Response to City of Carlsbad Third-Party Reviewer (First); dated November 13. 2020; 2.) Response to City of Carlsbad Third-Party Reviewer (Second); dated April 13, 2021. Smith Residence Job No. 18-11842 Carlsbad, California Page 2 FIELD OBSERVATIONS 1. Our representative was requested by the grading contractor, Hacienda Development Solutions between June 22 and June 28, 2021 to observe the grading and backfilling of the old canyon area located, approximately, near the center of the lot. The grading of the canyon area consisted of excavating approximately 12 feet below the finished grade surface (110.6 mean sea level), down to the dense formational Old Paralic Deposits (Qop2-4) and later backfilling the excavation. The loose soils encountered in the area of the new driveway were also removed down to firm natural soils and subsequently placed back and recompacted. Slope benches were properly made into the dense formational soils Qop2-4 as grading continued upslope to the east in the direction of the new residence, and to the north and west in the driveway area. A storm drain culvert running north to south was installed in the area of the old canyon. The canyon fill placement was observed and tested by our representative for proper compaction and moisture. 2. Our representative was requested by the grading contractor to observe the grading of the new residential building pad area intermittently between June 29, 2021 through March 11, 2022. The building pad was undercut approximately at least 4 feet below the proposed finished pad elevation of 110.6 feet into dense Qop2-4 prior to backfill placement. The garage building pad was moved to the southwest corner of the house instead of the northeast section portion as shown on the grading plan. The garage building pad was undercut approximately 3½ feet lower than the building pad undercut elevation to approximately 103.1 feet mean sea level. The bottom was observed to be founded in dense Qop2-4 prior to backfill placement. Smith Residence Job No. 18-11842 Carlsbad, California Page 3 On-site and imported soils were used for the backfill placement of the garage and residential building pads with the backfills predominantly consisting of imported soils. Imported soils were evaluated by our field representative and determined were determined to be suitable as backfill material. Approximately 5 feet of recompacted fill was placed in the garage excavation, and 4 feet approximately in the residential area of the building pad. The backfill placement was observed and tested by our representative. 3. Our representative was requested to intermittently observe and test the driveway soils between July 9 and November 19, 2021. The soils placed underneath the driveway consisted predominantly of on-site soil material with some areas containing small quantities of imported soils. 4. The storm drain culvert trench that runs perpendicular across the drive and north to south across the backfilled canyon was observed and tested by our representative on July 9. The storm drain excavation bottom was observed to be founded into dense Qop2-4 formational soils. Areas where soft or loose soils were encountered were removed and recompacted. 5. The soils placed around the perimeter of the north and south manhole boxes were observed and tested per the request of the contractor by our representative on August 31 and September 10, 2021. 6. The bearing soils for the footing excavations of the exterior site retaining walls were intermittently observed per the request of the contractor between September 24 and December 26, 2021. A joint was recommended to be added at the northeast end perimeter retaining wall and the south due to a transition layer. The joint was recommended at the top of the highest step. The Smith Residence Job No. 18-11842 Carlsbad, California Page 4 remaining portions of wall without transitions were founded on recompacted fill soils. 7. Backfill placement for the northside of the driveway retaining wall was observed and tested by our representative per the request of the contractor on November 19, 2021. Prior to backfill placement of the retaining wall, it was observed that the contractor had placed waterproofing on the wall but no drainage boards. Pictures were shown to our representative showing that the storm drain outlet discharges towards the rip rap dissipater located south of the driveway. It should be noted that it is not within the scope of our services to provide quality control oversight for surface or subsurface drainage construction or retaining wall sealing and base of wall drain construction. It is the responsibility of the contractor to verify proper wall sealing, geofabric installation, protection board installation (if needed), drain depth below interior floor or yard surfaces; pipe percent slope to the outlet, etc. 8. Backfill placement for the east side garage retaining wall was observed and tested per the request of the contractor by our representative on January 20 through January 21, 2022. The grading contractor placed 2 feet of gravel material at the bottom of the wall with a perforated PVC pipe wrapped with geofabric, followed by 2 feet of recompacted fill soils. 9. We understand that after reviewing this report, the city of Carlsbad may authorize foundation and slab construction for the residence structure. Smith Residence Job No. 18-11842 Carlsbad, California Page 5 SOIL TESTING Representative soil samples were collected during the grading to determine laboratory maximum dry density of the soils per ASTM D1557-12e1. Field density tests were performed at approximate locations shown on Figure No. II, Plot Plan in accordance with ASTM D6938-17a. The complete list of field density tests results is shown on Table A of Figure Nos. IIIa-b, and laboratory soil compaction test results are shown on Table B of Figure No. IIIc. Equipment used for the earthwork compaction consisted of a Mini-excavator, a Bob- cat with rubber tires. A water hose was used, when needed, to increase the soil moisture. Field density tests yielded a relative compaction of at least 90 percent of maximum dry density at the tested locations. Density tests were performed with a nuclear gauge testing apparatus in accordance with ASTM D6938-17a. The maximum dry density of the soils was determined per ASTM D1557-12e1. The on-site soil material used for the earthwork consisted of light and dark brown silty sand, and reddish-brown silty sand. The imported soils consisted of brown and dark brown clayey sand. The on-site soils were determined to have low expansion with an expansion index (E.I.) values less than 50. The imported soils were visually classified to have low expansion characteristics per ASTM D4829. Proper finish drainage for the site was to be implemented by the general contractor prior to completing construction. SITE SUITABILITY AND COMPLIANCE The observed and tested areas of the grading operation are, in our professional opinion, suitable for their intended use. The dense formational soils are, in our Smith Residence Job No. 18-11842 Carlsbad, California Page 6 professional opinion, suitable to support the recompacted fill, structure foundations, and new exterior improvements. We certify that the soil engineering aspects of grading are in general compliance with the approved soils report and the grading plans. LIMITATIONS The findings and opinions presented herein have been made in accordance with currently accepted principles and practice in the field of geotechnical engineering in the City of Carlsbad in the County of San Diego. No warranty, either expressed or implied, is made. All statements in this report are applicable only for the grading operation observed and tested by our firm. The firm Geotechnical Exploration, Inc. shall not be held responsible for fill soils placed without our observations and testing at any other time, or subsequent changes to the site by others, which directly or indirectly cause poor surface or subsurface drainage, water erosion, and/or alteration of the strength of the compacted fill soils. As previously stated, it is not within the scope of our services to provide quality control oversight for surface or subsurface drainage construction or retaining wall sealing and base of wall drain construction. It is the responsibility of the contractor to verify proper wall sealing, geofabric installation, protection board installation (if needed), drain depth below interior floor or yard surfaces; pipe percent slope to the outlet, etc. Smith Residence Job No. 18-11842 Carlsbad, California Page 7 In the event that any changes in the nature, design, or location of the building or improvements are planned, the conclusions and recommendations contained in this report should not be considered valid unless the changes are reviewed and the conclusions of this report modified or verified in writing. This opportunity to be of service is sincerely appreciated. If you have any questions regarding this letter, please contact our office. Reference to our Job No. 18-11842 will help expedite a response to your inquiry. Respectfully submitted, GEOTECHNICAL EXPLORATION, INC. _______________________________ ______________________________ Jaime A. Cerros, P.E. Leslie D. Reed, President R.C.E. 34422/G.E. 2007 C.E.G. 999/ PG 3391 Senior Geotechnical Engineer ______________________________ Richard A. Cerros, E.I.T. Staff Engineer Smith Residence 4246 Hillside Drive Carlsbad, CA. Figure No. I Job No. 18-11842 SITE VICINITY MAP Thomas Bros. Guide San Diego County, pg 1106-G6 59 Ap p r o x i m a t e L o c a t i o n of F i e l d D e n s i t y T e s t 1 3 4 2 5 7 6 8 9 15 13 14 16 12 17 28 24 27 25 26 23 21 20 19 11 22 18 10 2930 31 32 33 35 34 36 37 39 38 40 41 43 42 44 45 47 46 48 49 51 50 52 54 58 55 59 56 57 53 Ol d P a r a l i c D e p o s i t s , u n i t 2 - 4 Ar t i f i c i a l F i l l Qo p Qa f Qa f 2- 4 Qo p 2- 4 Qa f Qo p 2- 4 18 - 1 1 8 4 2 - P 3 . a i Sm i t h R e s i d e n c e 42 4 6 H i l l s i d e D r i v e Ca r l s b a d , C A . Fi g u r e N o . I I Jo b N o . 1 8 - 1 1 8 4 2 PL O T P L A N A N D SI T E S P E C I F I C GE O L O G I C M A P Le g e n d NO T E : T h i s P l o t P l a n i s n o t t o b e u s e d f o r l e g a l pu r p o s e s . L o c a t i o n s a n d d i m e n s i o n s a r e a p p r o x i m a t e . Ac t u a l p r o p e r t y d i m e n s i o n s a n d l o c a t i o n s o f u t i l i t i e s ma y b e o b t a i n e d f r o m t h e A p p r o v e d B u i l d i n g P l a n s or t h e “ A s - B u i l t ” G r a d i n g P l a n s . Ap r i l 2 0 2 2 GR A P H I C S C A L E ( F e e t ) Ge o l o g i c L e g e n d Ap p r o x i m a t e L i m i t s o f Ob s e r v e d G r a d i n g HILL S I D E D R I V E RE F E R E N C E : T h i s P l o t P l a n w a s p r e p a r e d f r o m a n e x i s t i n g L A N D S C A P E CO N S T R U C T I O N P L A N b y G R E G H E B E R T L A N D S C A P E A R C H I T E C T da t e d 1 1 / 7 / 1 9 a n d f r o m o n - s i t e f i e l d r e c o n n a i s s a n c e p e r f o r m e d b y G E I . TA B L E A App ro x i m a t e Wa t e r D r y De gre e o f T e s t E l e v a t i o n C o n t e n t D e n s i t y Co m pac t i o n C o m pac t i o n N o . Da t e o f T e s t T e s t L o c a t i o n (F e e t ) (%) (p cf ) (%) Cu r v e N o . R e m a r k s 1 6 / 2 2 / 2 1 C A N Y O N A R E A 9 3 . 5 9 . 8 11 7 . 3 91 2 O n s i t e 2 6 / 2 2 / 2 1 C A N Y O N A R E A 9 3 . 5 8 . 9 11 8 . 0 91 2 O n s i t e 3 6 / 2 2 / 2 1 C A N Y O N A R E A 9 3 . 5 1 0 . 0 11 9 . 2 92 2 O n s i t e 4 6 / 2 2 / 2 1 C A N Y O N A R E A 9 3 . 5 9 . 0 11 6 . 9 90 2 O n s i t e 5 6 / 2 2 / 2 1 C A N Y O N A R E A 9 3 . 5 8 . 6 11 7 . 7 91 2 O n s i t e 6 6 / 2 3 / 2 1 C A N Y O N A R E A 9 5 9 . 4 11 0 . 5 85 2 O n s i t e 7 6 / 2 3 / 2 1 C A N Y O N A R E A 9 5 10 . 4 1 1 1 . 6 91 1 O n s i t e 8 6 / 2 3 / 2 1 C A N Y O N A R E A 9 5 11 . 0 1 1 0 . 9 90 1 O n s i t e 9 6 / 2 3 / 2 1 C A N Y O N A R E A 9 5 10 . 1 1 1 2 . 0 91 1 O n s i t e 10 6 / 2 4 / 2 1 C A N Y O N A R E A 9 5 10 . 7 1 1 0 . 8 90 1 O n s i t e 11 6 / 2 4 / 2 1 C A N Y O N A R E A 9 5 11 . 3 1 1 1 . 4 90 1 O n s i t e 12 6/ 2 9 / 2 1 CA N Y O N A R E A 9 6 9. 9 1 1 1 . 9 91 1 O n s i t e 13 6/ 2 9 / 2 1 CA N Y O N A R E A 9 6 10 . 4 1 1 2 . 8 92 1 O n s i t e 14 6/ 2 9 / 2 1 CA N Y O N A R E A 9 6 9. 5 1 1 2 . 3 91 1 O n s i t e 15 6 / 2 8 / 2 1 C A N Y O N A R E A 97 9 . 6 1 2 1 . 4 94 2 O n s i t e 16 6 / 2 8 / 2 1 C A N Y O N A R E A 97 9 . 9 1 2 2 . 2 95 2 On s i t e 17 6 / 2 8 / 2 1 C A N Y O N A R E A 97 1 0 . 4 1 2 1 . 7 94 2 O n s i t e 18 7/ 7 / 2 1 GR A D I N G - B L D G P A D 10 7 . 5 1 0 . 2 1 0 8 . 0 90 3 On s i t e 19 7/ 7 / 2 1 GR A D I N G - B L D G P A D 10 7 . 5 1 2 . 8 1 1 4 . 4 93 1 On s i t e 20 7/ 9 / 2 1 GR A D I N G - B L D G P A D 10 4 1 0 . 2 1 1 1 . 6 91 1 On s i t e 21 7/ 9 / 2 1 GR A D I N G - D R I V E 10 5 9 . 3 1 1 8 . 1 91 2 On s i t e 22 7/ 1 8 / 2 1 GR A D I N G - D R I V E 95 7 . 2 1 1 3 . 6 92 1 On s i t e 23 7/ 1 8 / 2 1 ST D R A I N T R E N C H B F I L L 96 8 . 9 1 1 1 . 5 91 1 On s i t e 24 7/ 1 9 / 2 1 ST D R A I N T R E N C H B F I L L 96 . 5 1 1 . 2 1 1 1 . 9 91 1 On s i t e 25 7/ 1 9 / 2 1 GR A D I N G - D R I V E 97 7 . 2 1 1 6 . 9 90 2 On s i t e 26 8/ 1 2 / 2 1 GR A D I N G U P P E R P A D B L D G 10 9 . 5 7 . 6 1 1 9 . 6 91 4 Im p o r t 27 8/ 1 2 / 2 1 GR A D I N G U P P E R P A D B L D G 10 9 . 5 8. 3 12 0 . 1 91 4 Im p o r t 28 8/ 1 2 / 2 1 GR A D I N G U P P E R P A D B L D G 10 9 . 5 7 . 2 1 1 9 . 4 90 4 Im p o r t Jo b N o . 1 8 - 1 1 8 4 2 Fi g u r e N o . I I I a SU M M A R Y O F F I E L D D E N S I T Y T E S T R E S U L T S ( A S T M D 1 5 5 6 a n d / o r A S T M D 6 9 3 8 ) No t e s : 1 ) C u r v e n u m b e r r e f e r s t o T a b l e B 2 ) F S G d e n o t e s f i n i s h s u b g r a d e e l e v a t i o n 3 ) F B G d e n o t e s f i n i s h b a s e g r a d e e l e v a t i o n 4 ) F P G d e n o t e s f i n i s h p a v e m e n t g r a d e TA B L E A App ro x i m a t e Wa t e r D r y De gre e o f T e s t E l e v a t i o n C o n t e n t D e n s i t y Co m pac t i o n C o m pac t i o n N o . Da t e o f T e s t T e s t L o c a t i o n (F e e t ) (%) (p cf ) (%) Cu r v e N o . R e m a r k s SU M M A R Y O F F I E L D D E N S I T Y T E S T R E S U L T S ( A S T M D 1 5 5 6 a n d / o r A S T M D 6 9 3 8 ) 29 8/ 3 1 / 2 1 S. M A N H O L E 96 . 5 1 0 . 6 1 1 3 . 8 92 1 On s i t e 30 8/ 3 1 / 2 1 GA R A G E P A D 99 . 5 9 . 8 1 1 3 . 3 92 1 On s i t e 31 8/ 3 1 / 2 1 N. D R I V E W A Y 10 0 1 1 . 2 1 1 2 . 2 91 1 On s i t e 32 8/ 3 1 / 2 1 N. D R A I N A G E B O X 99 9 . 4 1 1 3 . 5 92 1 On s i t e 33 9/ 3 / 2 1 N. D R I V E W A Y 10 2 1 4 . 0 1 0 2 . 0 91 5 Im p o r t 34 9/ 3 / 2 1 N. D R I V E W A Y 10 4 1 3 . 7 1 0 3 . 1 92 5 Im p o r t 35 9/ 9 / 2 1 N. D R I V E W A Y 10 6 1 2 . 9 1 1 2 . 2 92 6 Im p o r t 36 9/ 1 0 / 2 1 N. D R A I N A G E B O X 10 2 1 3 . 0 1 1 1 . 8 92 6 Im p o r t 37 9/ 1 0 / 2 1 GA R A G E 10 2 1 2 . 4 1 1 2 . 5 92 6 Im p o r t 38 9/ 1 0 / 2 1 GA R A G E 10 2 1 3 . 2 1 1 2 . 0 92 6 Im p o r t 39 9/ 1 3 / 2 1 GA R A G E 10 4 1 3 . 9 1 1 2 . 2 92 6 Im p o r t 40 9/ 1 3 / 2 1 GA R A G E 10 4 1 4 . 2 1 1 2 . 0 92 6 Im p o r t 41 9/ 2 0 / 2 1 DR I V E W A Y 10 8 1 3 . 7 1 1 1 . 6 91 6 Im p o r t 42 9/ 2 2 / 2 1 DR I V E W A Y 11 0 1 1 . 2 1 1 2 . 5 91 1 On s i t e 43 9/ 2 8 / 2 1 DR I V E W A Y 10 4 1 0 . 7 1 1 3 . 1 92 1 On s i t e 44 9/ 2 8 / 2 1 DR I V E W A Y 10 4 1 1 . 0 1 1 2 . 7 91 1 On s i t e 45 11 / 1 9 / 2 1 DR I V E W A Y A R E A W A L L B A C K F I L L 10 1 . 5 1 2 . 9 1 1 1 . 8 92 6 On s i t e 46 11 / 1 9 / 2 1 DR I V E W A Y A R E A W A L L B A C K F I L L 10 3 . 5 1 3 . 7 1 1 2 . 6 92 6 On s i t e 47 11 / 2 4 / 2 1 DR I V E W A Y A R E A W A L L B A C K F I L L 10 5 1 2 . 0 1 1 0 . 9 91 6 On s i t e 48 1/ 2 0 / 2 2 HO U S E / G A R A G E E . R E T A I N I N G W A L L 10 6 1 3 . 1 1 1 0 . 4 90 6 On s i t e 49 1/ 2 0 / 2 2 HO U S E / G A R A G E E . R E T A I N I N G W A L L 10 6 1 1 . 8 1 1 0 . 0 90 6 On s i t e 50 1/ 2 0 / 2 2 HO U S E / G A R A G E E . R E T A I N I N G W A L L 10 8 1 2 . 4 1 1 1 . 2 91 6 On s i t e 51 1/ 2 0 / 2 2 HO U S E / G A R A G E E . R E T A I N I N G W A L L 10 8 1 1 . 5 1 1 2 . 0 92 6 On s i t e 52 1/ 2 1 / 2 2 HO U S E / G A R A G E E . R E T A I N I N G W A L L 10 8 1 2 . 1 1 1 0 . 3 90 6 Im p o r t 53 1/ 2 1 / 2 2 HO U S E / G A R A G E E . R E T A I N I N G W A L L 10 8 1 2 . 6 1 1 0 . 7 91 6 Im p o r t 54 1/ 2 1 / 2 2 HO U S E / G A R A G E E . R E T A I N I N G W A L L 11 0 1 1 . 9 1 1 3 . 0 93 6 Im p o r t 55 1/ 2 1 / 2 2 HO U S E / G A R A G E E . R E T A I N I N G W A L L 11 0 1 2 . 8 1 1 2 . 3 92 6 Im p o r t 56 3/ 1 1 / 2 2 HO U S E P A D F I N I S H 11 0 . 6 F S G 1 1 . 0 1 1 1 . 6 91 6 Im p o r t Jo b N o . 1 8 - 1 1 8 4 2 Fi g u r e N o . I I I b No t e s : 1 ) C u r v e n u m b e r r e f e r s t o T a b l e B 2 ) F S G d e n o t e s f i n i s h s u b g r a d e e l e v a t i o n 3 ) F B G d e n o t e s f i n i s h b a s e g r a d e e l e v a t i o n 4 ) F P G d e n o t e s f i n i s h p a v e m e n t g r a d e TA B L E A App ro x i m a t e Wa t e r D r y De gre e o f T e s t E l e v a t i o n C o n t e n t D e n s i t y Co m pac t i o n C o m pac t i o n N o . Da t e o f T e s t T e s t L o c a t i o n (F e e t ) (%) (p cf ) (%) Cu r v e N o . R e m a r k s SU M M A R Y O F F I E L D D E N S I T Y T E S T R E S U L T S ( A S T M D 1 5 5 6 a n d / o r A S T M D 6 9 3 8 ) 57 3 / 1 1 / 2 2 H O U S E P A D F I N I S H 1 1 0 . 6 F S G 1 0 . 7 11 0 . 9 91 6 I m p o r t 58 3 / 1 1 / 2 2 G A R A G E P A D F I N I S H 1 0 8 F S G 1 1 . 2 11 1 . 5 91 6 I m p o r t 59 3 / 1 1 / 2 2 G A R A G E P A D F I N I S H 1 0 . 5 11 2 . 9 92 6 I m p o r t Jo b N o . 1 8 - 1 1 8 4 2 Fi g u r e N o . I I I c No t e s : 1 ) C u r v e n u m b e r r e f e r s t o T a b l e B 2 ) F S G d e n o t e s f i n i s h s u b g r a d e e l e v a t i o n 3 ) F B G d e n o t e s f i n i s h b a s e g r a d e e l e v a t i o n 4 ) F P G d e n o t e s f i n i s h p a v e m e n t g r a d e J o b N o . 1 8 - 1 1 8 4 2 F i g u r e N o . I I I d TA B L E B LA B O R A T O R Y C O M P A C T I O N T E S T R E S U L T S ( A S T M D 1 5 5 7 ) Co m p a c t i o n M a x i m u m O p t i m u m T e s t S o u r c e o f D r y D e n s i t y W a t e r C o n t e n t C u r v e N o . D e s c r i p t i o n o f M a t e r i a l M a t e r i a l ( p c f ) % C- 1 R E D - B R O W N S I L T Y S A N D ( S M ) 1 2 3 . 2 1 1 . 5 C- 2 D A R K B R O W N S I L T Y S A N D ( S M ) 1 2 9 . 3 9 . 3 C- 3 L I G H T B R O W N S I L T Y S A N D ( S M ) 1 1 9 . 7 1 1 . 3 C- 4 D A R K B R O W N C L A Y E Y S A N D ( S C ) I m p o r t 1 3 2 . 0 8 . 0 C- 5 B R O W N S A N D Y C L A Y ( C L ) I m p o r t 1 1 2 . 2 1 3 . 5 C- 6 B R O W N A N D Y C L A Y / C L A Y E Y S A N D ( C L / S C ) I m p o r t 1 2 2 . 1 1 2 . 2