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HomeMy WebLinkAboutX2020-2298 - Soils01 COAST GEOTECHNICAL, INC. 202�-Z+ C� I�Wu�or+ CinaVI�J 1200 W. Commonwealth Avenue, Fullerton, CA 92833 Pb-, (714) 370-1211 Fax: (714) 870-12?2� E-mail: coastgeotecQsb global.net July2l, 2021 W.0.591220-03 Mayo Family Trust C/o Mr. Jeremy Grissinger 1863 Port Renwick Place Newport Beach, CA 92660 Subject: Rough Grade Compaction Report for 1844 Port Charles Place, Newport Beach, California References: 1. Geotechnical Engineering Investigation of Proposed New Residence 1844 Port Charles Place, Newport Beach, California; by Coast Geotechnical, Inc., W.O.591220-01, dated May 26, 2020. 2. Response to Geotechnical Report Review Checklist, at 1844 Port Charles Place, Newport Beach, California; by Coast Geotechnical, Inc., W.O.591220-02, dated December 7, 2020. Gentlemen: Forwarded herewith is the rough grade compaction report for the subject site. PLACEMENT OF FILL The grading operation was conducted between July 6, 2021 and July 14, 2021 for the basement area only, utilizing the referenced geotechnical reports. A gravel mat was placed on the subject site to provide adequate support for the proposed mat slab of the basement. Temporary excavations were sloped at 1:1 H:V slope gradients outside the basement perimeter. The bottom of the basement was stabilized with approximately 18 to 24 inches of 3/< inch crushed rock underlain by Mirafi 500x geotextile. Two fiberglass sump tanks were installed approximately four feet below the pad grade of the basement and backfill with cement slurry. OverexcavVi2p-.of.tbe.,basement. Pad, extended into native earth material. Duetosaturated soil conditions and water seepage, a % inch crushed rock mat approximately 18 to 24 inches thick was be placed on the bottom of the basement excavation to achieve design grade, The seepage water was controlled through the rock mat to a small sump pump. The rock mat was rolled to a firm and unyielding condition. The basement grading plan provided by Forkert Engineering and Surveying, is attached as Plate 1. The basement excavation and laybacks are considered stable for temporary conditions. Subsequent grading will be conducted upon completion of the basement walls. Grading will consist of backfill of basement was, over -excavation and recompaction of the at -grade foundation areas as well as over -excavation and recompaction of the proposed pool area. COAST GEOTECHNICAL, INC Mayo Family Trust 2 W.O.591220-03 Rough Grade Compaction Report July 21 2021 Equipment used for compacting the fill soils consisted of a Cat excavator and a Cat track loader. Earthwork was by RB Holt, Inc. RECOMMENDATIONS AND CONCLUSIONS Due to varied subsurface soil conditions the proposed residence has been designed with a mat foundation to support the structure. The mat foundation may utilize an allowable bearing value of 1,500 psf, a modulus of subgrade reaction of 100 psi in the design, and is designed to be at least twelve inches thick. At grade areas of the foundation outside the basement shall have a perimeter footing extending a minimum of 24 inches below lowest adjacent grade and structural slab to be at least twelve inches thick. This value is for dead plus live load and may be increased 1/3 for total including seismic and wind loads where allowed by code. This basement mat slab will utilize a concrete waste slab to provide a better working platform and a better surface on which to place a waterproof membrane. The waterproofing membrane may be covered with a protection slab prior to placing the mat foundation. A waterproof specialist shall be consulted for specific design recommendations. Foundations outside the basement shall be reinforced with a minimum of four #5 bars, two top and two bottom. Actual reinforcement shall be in accordance with the structural engineer's details. Where isolated pads are utilized, they shall be tied in two directions into adjacent foundations with grade beams. Footing excavations shall be observed by a representative of COAST GEOTECHNICAL, INC. prior to placement of steel or concrete to verify soil conditions. Proposed property line walls may be supported by continuous spread footings placed a minimum depth of 24 inches below lowest adjacent grade utilizing an allowable bearing value of 1,500 pounds per square foot. Some mitigation of footing bottoms (deepening) and or compacting should be expected and will be field determined. Footing excavations shall be observed by a representative of COAST GEOTECHNICAL, INC. prior to placement of steel or concrete to verify competent soil conditions. lf unacceptable soil conditions are exposed mitigation will be recommended. LATERAL PRESSURES Lateral restraint at the base of footings and on slabs may be assumed to be the product of the dead load and a coefficient of friction of 0.30. Passive pressure on the face of footings may also be used to resist lateral forces. A passive pressure of zero at the surface of finished grade, increasing at the rate of 350 pounds per square foot of depth to a maximum value of 3,500 pounds per square foot, maybe used for compacted fill at this site. Where passive pressure and friction are combined when evaluating the lateral resistance, the value of the passive pressure should be limited to 2/3 of the values given above. COAST GEOTECHNICAL, INC Mayo Family Trust 3 W.O. 591220-03 Rough Grade Compaction Report July 21 2021 FLOOR SLABS Where a slab on grade is utilized, the mat slab she be supported on engineered fill compacted to a minimum of 90% relative compaction. Both the basement slab and the at -grade level floor slab are recommended to be designed as structural slabs. Slab on grades shall be designed in accordance with CBC codes. Concrete slabs supported by engineered fill soil may be designed utilizing values of 1.0 for Co and 1.0 for Cs with an effective plasticity index of 20, and in accordance with publications or methods stated in the appropriate section of the building code. Minimum geotechnical recommendations for a structural slab design are 12 inches actual thickness, with reinforcement as determined by the structural engineer. If the soils at grade become disturbed during construction, they shall be brought to 2-3% over optimum moisture content and compacted to a minimum of 90% relative compaction prior to placing concrete. COAST GEOTECEMCAL, Inc. will need to verify adequate mitigation. The subgrade soil should be kept moist prior to casting, the slab. However, if the soils at grade become disturbed during construction, they should be brought to approximately optimum moisture content and rolled to a firm, unyielding condition prior to placing concrete. The capillary break material shall comply with the requirements of the local jurisdiction and shall be a rninimum of four inches in thickness and consist of gravel (1/2-inch or larger clean aggregate). A heavy filter fabric should be placed over the gravels prior to placement of the recommended vapor retarder to minimise puncturing of the vapor retarder. Slab areas should be underlain by a vapor retarder consisting of an engineered plastic film (as described by ASTMiE-1745). A vapor barrier with a permeance of less than 0.01perms (consistent with ACI 302.2R-06) such as 15 mil. Stego Wrap Vapor Barrier, or equivalent should be considered The vapor barrier should be underlain by the above described capillary break material and filter cloth. The capillary break materials should be compacted to a uniform condition prior to placement of the recommended filter cloth and vapor barrier. The vapor barrier should be properly lapped and sealed and in contact with the slab bottom. Waterproofing of basement floors and wall should be considered to further minimise the potential for moisture problems. The client should consult with a waterproofing expert on basement slab and wall protection. BASEMENT WALL DESIGN Basement walls may be designed for "at -rest" earth pressure of 66.3 pcf if a subdrain system is employed to relieve hydrostatic pressure. To alleviate the need for a permanent sump and continual operation, the basement wall subdrains may be eliminated, provided basement walls are designed for the added hydrostatic pressure. The equivalent fluid pressure with hydrostatic COAST GEOTECHNICAL, INC Mayo Family Trust 4 W.O. 591220-03 Roush Grade Compaction Report July 21 2021 pressure is 95.8 pef. The equivalent fluid pressure with hydrostatic pressure and seismic loading is 123.6 pcf for a restrained condition. Basement walls may be designed for unrestrained conditions using an active earth pressure of 40 pcf (see Plate j) if a subdrain system is employed to relieve hydrostatic pressure. To alleviate the need for a permanent sump and continual operation, the basement wall subdrains may be eliminated, provided basement walls are designed for the added hydrostatic pressure. The equivalent fluid pressure with hydrostatic pressure is 85.1 pcf (see Plate M). The seismic loading for level and unrestrained condition is 16.4 pcf as shown on Plate K. The equivalent fluid pressure with hydrostatic pressure and seismic loading is 101.5 pcf for an unrestrained condition. Based on the depth of the existing seepage water level (approximately eight feet below grade), a hydrostatic uplift pressure should be considered Due to the potential for seepage water to enter the basement excavation a conservative hydrostatic uplift force of two feet should be also considered in the mat foundation design, for a ten foot deep basement. More hydrostatic uplift should be considered if basement is deeper than ten feet. Uplift pressure equals 62.4 pef times the distance of elevated water from the base of the mat foundation. BASEMENT WALL BACICHLL Basement wall backfill shall consist of import materials with a very low expansion potential or gravels, and shall be capped with at least three feet of cohesive on -site or imported soil to lessen the infiltration of water. Where gravels are utilized the gravels shall be wrapped in filter fabric. All backfills shall be placed in thin lifts and compacted to a minimum of 90% relative compaction under the observation and testing of the soils engineer. WATERPROOFING There is an inherent risk with moisture problems when constructing below grade rooms. The geotechnical consultant is only responsible for identification of adverse moisture conditions, which will impact below grade rooms at this site. The waterproofing for the basement floor and walls should be designed accordingly by a qualified person. Basement floors and walls should be designed watertight. SEISNIIC DESIGN Based on the current CBC and ASCE7-16, the following seismic design parameters are provided. These seismic design values were determined utilizing latitude 33.62498 and longitude - 117.85710 and calculations from the SEAOC/OSBPD seismic design parameter calculator. A conservative site class D was assigned to site earth materials. A printout of the data is attached in Appendix B. • Site Class = D • Mapped 0.2 Second Spectral Response Acceleration, Ss = 1.31lg • Mapped One Second Spectral Response Acceleration S, = 0.466g COAST GEOTECHNICAL, INC Mayo Family Trust 5 W.O.591220-03 Rough Grade Compaction Report July 21 2021 • Site Coefficient from Table 1613A5.3(1), Fa = 1.0 • Site Coefficient from Table 1613A53(2), Fv = *null • Maximum Design Spectral Response Acceleration for short period, SM, = 1.311 g • Maximum Design Spectral Response Acceleration for one -second period, SM, = *null • 5% Design Spectral Response Acceleration for short period, Sos = 0.874g • 5% Design Spectral Response Acceleration for one -second period, SDI = *null *null - see section 11.4.8 ASCE 7-16 CHEMICAL ANALYSIS An on -site soil samples showed a negligible soluble sulfate content. Per the CBC, type II concrete with a minimum of 2,500 psi compressive strength may be used. SETTLEMENT Total settlement of the foundation as recommended and subject to the allowable loads is anticipated to be on the order of one -inch, accompanied by differential settlement on the order of 3/4- inch over forty feet of horizontal distance. EXPANSIVE SOILS Results of expansion tests indicate that the near surface soils have a medium expansion potential. The medium recommendations on the accompanying Expansive Soil Recommendations Chart, Plate A, shall be utilized in the design. UTILITY LINE BACIUMLS All utility line backfills, both interior and exterior, shall be compacted to a minimum of 90% relative compaction and shall require testing at a minimum of two -foot vertical intervals. The client and contractor are advised that failure to have proper geotechnical observation and testing of trench backfills could result in our final soils report for the project being rejected by the City. It is the responsibility of the client or his agent to request needed services from COAST GEOTECFINICAL, Inc. Utility lines shall be located outside a 451 degree line projected downward from a foundation's bottom edge. Where below grade utility lines enter a building footprint, a significant section of the trench shall contain a compacted cohesive fill or slurry backfill plug to mitigate the migration of waters through permeable backfill soils into interior building areas. DRAINAGE Positive drainage should be planned for the site. Drainage should be directed away from structures via non -erodible conduits to suitable disposal areas. The structure should utilize roof gutters and down spouts tied directly to yard drainage. COAST GEOTECHNICAL, INC Mayo Family Trust 6 W.O. 591220-03 Roush Grade Compaction Report July 21 2021 Unlined flowerbeds, planters, and lawns should not be constructed against the perimeter of the structure. If such landscaping (against the perimeter of a structure) is planned, it should be properly drained and lined or provided with an underground moisture barrier. Irrigation should be kept to a minimum. While the CBC recommends 5% slope away from structures for landscape areas, 2% slope is allowable where justified. Our justification is the use roof drains tied into area drains, the use of area drains, and site grading which will mitigate the potential for moisture problems beneath a slab on grade. Hardscape areas shall be sloped a minimum of 2% where within ten feet of the residence unless allowed otherwise by the building official. We do not recommend the use of infiltration best management practice (BMP) such as infiltration trenches, infiltration basins, dry wells, permeable pavements, subsurface reservoir beds, or similar systems designed primarily to percolate water into the subsurface soils due to the potential for infiltration waters to adversely affect below grade rooms, building foundations and slabs, hardscape, pavement and other site improvements. We recommend that site waters be passed through an approved filtration system and discharged to an approved drainage system. The WQMP requirements shall be addressed by the Civil Engineer. HARDSCAPE Hardscape and slab subgrade areas shall exhibit a minimum of 90% relative compaction to a depth of at least two feet. Deeper removal and recompaction may be required if unacceptable conditions are encountered. These areas require testing just prior to placing concrete. Minimum slab thickness shall be five inches and reinforced with #3 bars at 18 inches on center each way. Exterior hardscape slabs will be subject to volume changes in subgrade soils, which may lead to cracking. Movement of slabs adjacent to structures can be mitigated by doweling slabs to perimeter footings. Doweling should consist of No. 4 bars bent around exterior slabs. Doweling should be spaced no farther than 36 inches on centers. As an option to doweling, an architectural separation could be provided between the main structure and abutting appurtenance improvements. Presaturation of exterior slab areas is also desirable. At exterior edges of patios and other flatwork, a cut -oil wail to a depth of at least eight inches is highly recommended. If no significant load is associated with the edge of the slab, the width of the cut-off wall may be limited to eight inches. Reinforcement adopted for the main structure may be applied to the appurtenances. As an alternative to rigid hardscape or brickwork, flexible pavers maybe utilized. POST -GRADING SERVICES During construction of the residence, it is recommended, and at times required by the regulatory agency, the following be observed and/or tested by the geotechnical engineer: • Backfill placement of basement area • Grading at -grade areas COAST GEOTECHNICAL, INC Mayo Family Trust 7 W.O. 591220-03 Rough Grade Compaction Report July 21 2021 • Excavation of foundations • Backfill of interior slab areas • Backfill of exterior utility trenches Pool grading and excavation • Hardscape subgrade testing It is the responsibility of the developer to schedule the required observations and testing. REGULATORY COMPLIANCE I hereby certify that the subject grading was observed by a representative from this office, and the work was done in full compliance with the Grading Ordinance of the City of Newport Beach and in accordance with the best accepted practices of the applicable chapter of the California Building Code. All cuts, fills or processing of original ground under the purview of this report have been completed under the observation of and with selective testing by COAST GEOTECHNICAL, Inc., and found to be in compliance with the Grading Cade of the City of Newport Beach. The completed work has been observed by COAST GEOTECHNICAL, Inc., and is considered adequate for the development. Our findings were wade and recommendations prepared in accordance with generally accepted professional engineering practices, and no further warranty is implied nor made. This report is subject to review by the controlling authorities for this project. We appreciate this opportunity to be of service to you. Respectfully submitted: COAST GEOTECHNICAL, INC. Ming-T g Ch RCE 54011 Damel E. erH- c Staff Geologist v C § a 3?29 gg 2i § x{a 9 3fia fie fid esafi `fi3$�@Ed�e�'a»»�� @ !3gg¢gyy��@ ��jj,,�p u g$5'��� yy p6 sgga a yg� g@ggaeaaaeneea d s966»9�aafia`e$�e::eaeeax63aaa.353fi3axxx�:3a6aE9ea€apPnakaa y� [�] Wig 5 3a f w I ED 5 jj 1 i 141ht� I ( 1 �� � � � � k. '1l� I I i� F a I � -� d — eesa v. x •.. \'� t is $6� tlt �sa a 9!aQ�a tg q! x� @ppfi�a 93Y333Y a{ x �p ag3Qa' F, k 3 @ pia 1 R pil 3 COAST GEOTECHINTICAL, INC. 1200 west Conunomvealth Avenue, Fullerton. CA 92833 Ph:714-870-1211 Fas:714-870-1222 e-mail:coastgeotec@1 sbcglobal.net October 28, 2022 Mayo Family Trust C/o Mr. Jeremy Grissinger 11912 Arroyo Ave. Santa Ana, CA 92705 References: W.O.591220-04 Subject: Final Soils Report for 1844 Port Charles Place, Newport Beach, California 1. Geotechnical Engineering Investigation of Proposed New Residence 1844 Port Charles Place, Newport Beach, California; by Coast Geotechnical, Inc., W.O.591220-01, dated May 26, 2020. 2. Response to Geotechnical Report Review Checklist, at 1844 Port Charles Place, Newport Beach, California; by Coast Geotechnical, Inc., W.O.591220-02, dated December 7, 2020. 3. Rough Grade Compaction Report for 1844 Port Charles Place, Newport Beach, California; by Coast Geotechnical, Inc., W.O.591220-03, dated July 19, 2021. Dear Mr. Grissinger: In accordance with your request, this final soils report has been prepared to address geotechnical observations and testing performed since completion of rough grading. This report addresses requested observations and testing. Copies of our daily reports are maintained in our files. FOUNDATION EXCAVATIONS The basement waste slab of the mat slab foundation system was observed on July 21, 2021. The at -grade foundation excavations were observed on October 11, 2021. The foundation excavations were found to be acceptable at the time of our final observation. INTERIOR SLAB SUBGRADE AND TRENCH BACKFILLS The at -grade mat slab subgrade was observed on October 15 & 18, 2021. Probing and testing of the slab subgrade areas showed acceptable geotechnical conditions for support of the proposed slab. BASEMENT WALL BACKFILL Backfill of the basement walls, as requested periodically by the contractor, was observed from September 13, 2021 through October 18, 2021. The basement walls were initially backfilled with about three feet of cement slurry prior to placing import material. The backfill consisted gravel with a soil cap. The soil and gravel was separated by filter cloth. COAST GEOTECHNICAL, INC. Mayo Family Trust 2 W. O. 591220-04 Final Soils Report October 28, 2022 Gravels were compacted in thin lifts to and unyielding condition prior to placing a three to four foot thick soil cap. Backfill soils were placed in thin lifts; moisture conditioned as needed and mechanically compacted to a minimum of 90% relative compaction up to finish pad grade elevations. Equipment used for compaction of fill soils consisted of mechanical hand compactors. Earthwork was completed by Altergott Construction. HARIDSCAPE Hardscape subgrade areas for the driveway, patio, and side walkways were observed on August 8 & 9, 2022. Probing and testing of hardscape area subgrades indicated acceptable geotechnical conditions for support of the proposed hardscape. OPINION It is opinion of COAST GEOTECHNICAL, INC. that the summarized geotechnical conditions approved by this office are in compliance with approved geotechnical reports and Newport Beach building codes. The final grades appear to conform to approved plans. We appreciate this opportunity to be of service to you. Respectfully Submitted: COAST GEOTECHNICAL, INC. Ming-Tarng Chen RCE 54011 No.$4011 Exp. 12/31/23 IV 4aniel E. Herc Staff Geologist