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HomeMy WebLinkAboutX2018-3239 - Soils (2)COAST GEOTECHNICAL, INC. 1200 W Commonwealth Avenue, Fullerton, CA 92833 Ph: (714) 870-1211 Fax: (714) 870-1222 Email: coastgeotec@sboglobal.net July 1, 2019 Mr. Gary Uecker C/o C.J. Light Associates 1401 Quail Street, Suite 120 Newport Beach, CA 92660 References: W.O. 544317-03 Subject: Rough Grade Compaction Report for Proposed New Residence at 1076 Pescador Drive, Newport Beach, California 1. Geotechnical Engineering Investigation of Proposed New Residence at 1076 Pescador Drive, Newport Beach, California; by COAST GEOTECHNICAL, INC., W.O. 544317-01, dated January 17, 2018. 2. Response to First Geotechnical Report Review Checklist for New Residence at 1076 Pescador Drive, Newport Beach, California, by COAST GEOTECHNICAL, INC., W.O. 544317-02, dated January 31, 2019. Dear Mr. Uecker: Forwarded herewith is the rough grade compaction report for the subject site. The grading operation for construction of the building pad was conducted from June 18, 2019 through June 26, 2019. PLACEMENT OF FILL Compacted fill material was placed on the subject site to provide adequate support for the proposed structure. Overexcavation extended down to competent native earth material. The depth of the overexcavation was approximately three to four and a half feet below finish grade for the house pad. The bottom of the excavations exposed competent material. The exposed surface was scarified, heavily watered, and compacted to a minimum of 90% relative compaction. Subsequent fills were placed in six to eight inch loose lifts and compacted to a minimum of 90% relative compaction by rubber tire loader. Import soil was used to get finish pad grade elevations. This process was followed to final grade. Limits of grading are shown on the attached Plate 1. COAST GEOTECHNICAL, INC. Mr. Gary Uecker 2 W.O. 544317-03 Rough Grade Compaction Report July 1 2019 Equipment used for the compaction of fill soils consisted of a Cat 973D track loader and Kubota SVL95 rubber track loader. Soils were moisture conditioned by a water hose as needed. Earthwork was by Tight Quarters Inc. TESTING Maximum density optimum moisture relationship determinations were performed for each soil type encountered during grading operations. Test results were as follows: Laboratory Standard: (ASTM:D-1557) 4 -inch diameter mold; 1/30 ft3 volume.; 5 layers at 25 blows per layer; 10 lb. hammer dropped 18 inches Compaction tests were performed a minimum of every two feet and/or 500 cubic yards of compacted fill soils placed. These tests were performed in accordance with ASTM test methods. The test results are summarized in Table 1. The approximate test locations are shown on Plate 1. FOUNDATIONS ON COMPACTED FILL Foundations for the proposed residence shall be supported by continuous spread footings or isolated pads placed a minimum depth of 24 inches below lowest adjacent grade inches utilizing an allowable bearing value of 1,800 pounds per square foot. Minimum foundation width shall be fifteen inches. 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. Isolated pads shall be connected to adjacent foundations in at least two directions with grade beams or continuous footings. It is recommended that all footings be reinforced with a minimum of four. #5 bars (two top and two bottom). The structural engineer's reinforcing requirements should be followed if more stringent. Footing excavations shall be observed by a representative of COAST GEOTECHNICAL, Inc. pnor to p acement of steel or concrete to verify competent soil conditions. If unacceptable soil conditions are exposed mitigation will be recommended. sification OM41sture% Max DryDens3? Brown Silty Sand 9.5 _ . 125.0 ty, Sandy Clay NVI 12.0 118.0 wn Silty, Slightly10.0 127.0 ey Sandray Siltstone 13.0 110.0 Compaction tests were performed a minimum of every two feet and/or 500 cubic yards of compacted fill soils placed. These tests were performed in accordance with ASTM test methods. The test results are summarized in Table 1. The approximate test locations are shown on Plate 1. FOUNDATIONS ON COMPACTED FILL Foundations for the proposed residence shall be supported by continuous spread footings or isolated pads placed a minimum depth of 24 inches below lowest adjacent grade inches utilizing an allowable bearing value of 1,800 pounds per square foot. Minimum foundation width shall be fifteen inches. 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. Isolated pads shall be connected to adjacent foundations in at least two directions with grade beams or continuous footings. It is recommended that all footings be reinforced with a minimum of four. #5 bars (two top and two bottom). The structural engineer's reinforcing requirements should be followed if more stringent. Footing excavations shall be observed by a representative of COAST GEOTECHNICAL, Inc. pnor to p acement of steel or concrete to verify competent soil conditions. If unacceptable soil conditions are exposed mitigation will be recommended. COAST GEOTECHNICAL, INC. Mr. Gary Uecker 3 W.O. 544317-03 Rough Grade Compaction Report July 1 2019 FOUNDATIONS ON NATIVE SOILS Secondary structures may be supported by continuous spread footings placed a minimum depth of 24 inches below lowest adjacent grade may utilize an allowable bearing value of 1,500 pounds per square foot. 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. It is recommended that all footings be reinforced with a minimum of four # 5 bars (two top and two bottom). The structural engineer's reinforcing requirements should be followed if more stringent. A representative of COAST GEOTECHNICAL, Inc. shall observe foundation excavations to verify that they comply with project geotechnical recommendations. Some mitigation of footing bottoms (deepening or compaction) should be anticipated. LATERAL DESIGN 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 increasing at the rate of 300 pounds per square foot of depth to a maximum value of 3000 pounds per square foot may be used for compacted fill and native soil at this site. If 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. RETAINING WALLS Walls retaining drained earth under static loading may be designed for the following: The code requires that retaining walls supporting more than six feet of backfill be designed for earthquake ground motions. A supplemental report will be needed if final plans show this condition to exist. The client is advised that seismic loads will be high due to high ground motion and current City policy. The point of resultant force under static loading is at H/3 above the base of the retaining wall. Footing excavations require the observation and approval by COAST GEOTECHNICAL, Inc. and the City grading inspector. COAST GEOTECHNICAL, INC. Mr. Gary Uecker 4 W.O. 544317-03 Roush Grade Compaction Report July 1, 2019 WATERPROOFING There is an inherent risk associated with moisture -induced problems when constructing earth retaining structures. The client, the design consultant of the waterproofing system, and the contractor responsible for installation, assumes this risk. The geotecbnical consultant is only responsible for identification of adverse moisture conditions, which could impact below grade rooms. Site basement walls and floors shall be waterproofed to the degree desired by the client. Waterproofing design is not within the expertise or work scope of the soils engineer. SUBDRAINS Subdrain systems shall be installed behind retaining walls and at a minimum they shall consist of four -inch diameter SCH 40 or SDR 35 perforated pipe surrounded with one cubic foot, per lineal pipe foot, of 3/4 -inch gravel. The gravel shall be wrapped in filter fabric. Outlet pipes shall be solid pipe of similar material. Subdrain systems shall be independent of area surface drains and roof drains. Subdrain placement requires observation and approval by COAST GEOTECHNICAL, Inc. RETAINING WALL BACKFILL Retaining wall backfills shall consist of onsite granular import earth materials, gravels, or where allowed and or designed for onsite earth materials. The project soils engineer shall be consulted prior to the import of any select backfill to verify that the import material complies with our recommendations for select material. At a minimum the material shall have an expansion index of zero and a minimum phi angle of 30 degrees. Materials typically utilized are pea gravels, 3/4 -inch gravels, and clean sand. Where gravel is utilized, the gravel shall be separated from soil by filter cloth. The upper two to three feet of backfill shall be with a cohesive onsite or import soil to reduce infiltration of surface water. Prior to placement of any backfills the area shall be cleaned of loose soils and construction debris. COAST GEOTECHNICAL, Inc. shall observe and approve the area as acceptable prior to any backfill placement. Retaining wall backfill shall be placed in six to eight inch loose; moisture conditioned lifts and mechanically compacted to a minimum of 90% relative compaction. Backfills require testing at two -foot vertical intervals during placement. Compaction of backfills requires observation and approval by COAST GEOTECHNICAL, Inc. COAST GEOTECHNICAL, INC. Mr. Gary Uecker 5 W.O. 544317-03 Rough Grade Compaction Report July 1 2019 SETBACK Foundations shall maintain a setback as measured horizontally from the bottom outside footing edge to a descending slope face of H/3 where H is the slope height. Based on a slope height of about twenty-three feet, a minimum eight -foot setback is recommended. DECK & PLANTER WALLS Foundations on or at the top of slope, may consist of a pile and grade beam foundation system that maintains at least an eight -foot foundation setback from the slope face. Where piles are necessary they shall be at least 18 inches in diameter and shall extend at least five feet into compacted fill or native soil below the creep zone. Piles may be designed using a skin friction value of 400 psf per foot of intercept with compacted fill or native soil with a point of fixity taken at five feet. Piles shall be interconnected with grade beams. The weight of the pile and grade beams may be neglected in considering dead loads. Structural design shall determine actual depth requirements based on loading. 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. Foundation excavations shall be observed by a representative of COAST GEOTECHNICAL, INC. prior to placement of steel and/or concrete to verify compliance with geotechnical recommendations. If unacceptable conditions are exposed mitigation will be required. CREEP LOAD Creep loads may impact proposed site improvements near the descending slope. Proposed foundations and site improvements located within ten feet of this top of slope or located on this slope shall incorporate a creep value of 1,000 pounds per foot of depth for the upper three feet of earth material. Passive pressures shall be ignored in the creep zone. SEISMIC DESIGN Based on the 2016 CBC the following seismic design parameters are provided. These seismic design values were determined utilizing latitude 33.62468 and longitude -117.8976 and calculations from the USGS Seismic Tool Application. A conservative site class D was assigned to site earth materials. A printout of the USGS Seismic Tool output is attached in Appendix B. • Site Class = D • Seismic Design Category = D • Mapped 0.2 Second Spectral Response Acceleration, Ss = 1.697g • Mapped One Second Spectral Response Acceleration St = 0.624g • Site Coefficient from Table 1613A.3.3(1), Fa =1.0 • Site Coefficient from Table 1613A.3.3(2). Fv = 1.5 • Maximum Design Spectral Response Acceleration for short period, Sm, = 1.697g • Maximum Design Spectral Response Acceleration for one -second period, SMl = 0.936g COAST GEOTECHNICAL, INC. Mr. Gary Uecker 6 W.O. 544317-03 Roush Grade Compaction Report July 1. 2019 • 5% Design Spectral Response Acceleration for short period, SDs = 1.132g • 5% Design Spectral Response Acceleration for one -second period, SDI= 0.624g SETTLEMENT For a structure supported by foundations placed into approved earth materials the maximum total post -construction settlement is anticipated to be on the order of one-half inch. Differential settlements are expected to be less than 3/4 inch, measured between adjacent structural elements over a horizontal distance of forty feet. EXPANSIVE SOILS Results of expansion tests indicate that the near surface soils have a medium expansion potential. SUBSIDENCE & SHRINKAGE Subsidence over the site is anticipated to be negligible. Shrinkage of reworked materials should be in the range of 5 to 10 percent. SOLUBLE SULFATES A chemical analysis of typical near surface earth materials for soluble sulfates showed a sulfate content of 75 ppm. Based on the current CBC and Table 4.3.1 of ACI 318-05 this is a negligible exposure to sulfate corrosion. Type II cement may be utilized. Structural requirements may dictate a higher strength concrete. FLOOR SLABS Proposed interior slabs shall derive support from compacted fill. Site materials are expansive in nature. Guidelines in the current CBC shall be utilized in the design of slabs. For design of slab on grade a computed effective plasticity index of 18 may be utilized. Minimum geotechnical recommendations for on grade slab design are five inch actual thickness with #4 bars at twelve inches on center each way. Structural design may require additional reinforcement and slab thickness. If the soils at grade become disturbed during construction, they should be brought to 34% over optimum moisture content and recompacted to a minimum of 90% relative compaction. Prior to placement of the capillary break and or vapor barrier COAST GEOTECHNICAL, Inc., shall test the slab subgrade soils for moisture content and compaction. The capillary break -material- shallcomply-with-the requirements -of thelocaljurisdiction and - shall be a minimum 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 COAST GEOTECHNICAL, INC. Mr. Gary Uecker 7 W.O. 544317-03 Roueh Grade Compaction Report July 1, 2019 recommended vapor retarder to minimize puncturing of the vapor retarder. Additionally, a vibratory plate should be used over the gravels prior to placement of the filter fabric to smooth out any sharp protuberances and consolidate the gravels/sands. Slab areas should be underlain by a vapor retarder consisting of an engineered plastic film (as described by ASTM:E-1745). In areas where a moisture sensitive floor covering will be used and/or where moisture infiltration is not desirable, 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. TEMPORARY CUTS Temporary construction cuts, based on preliminary plans, are anticipated for the grading Temporary cuts in site earth materials are anticipated to expose existing fill soil and shall be sloped at a 1:1(H:V) angle. No cuts shall be allowed which would remove significant runs of lateral support from adjacent properties, structures, or public right of ways. Typically construction cuts where these conditions exist shall be restricted to a 1:1 downward projection to the excavation bottom. Alternate construction methods may need to be used along the return property line walls of the toe of slope retaining wall. The project geologist shall observe all cuts at the time of excavation. If adverse conditions are exposed, remedial measures will be recommended and implemented. OSHA guidelines shall be followed where workers are to enter confined spaces, trench work, or excavations. UTILITY LINE BACKFILLS All utility line backfills, both interior and exterior, shall be compacted to a minimum of 90% relative compaction and shall require testing at a maximum of two -foot vertical intervals. Utility lines shall be placed at appropriate depths. Shallow pipes can be damaged by the forces imposed by compacting backfill soils. If shallow pipes are not capable of withstanding the forces of backfill compaction, slurry backfill will be recommended. COAST GEOTECHNICAL, INC. shall be present during backfill placement and compaction to verify_compliars . COAST GEOTECHNICAL, INC. Mr. Gary Uecker 8 W.O. 544317-03 Rough Grade Compaction Report July 1, 2019 HARDSCAPE AND SLABS 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. Hardscape shall be at least four inches thick and reinforced with 94 bars on 18 inch centers both ways. 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. Drainage shall not be directed onto or over slopes. 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 current 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 bottomless trench drains to conform with infiltration best management practice (BMP) such as infiltration trenches, infiltration basins, dry wells, permeable pavements or similar systems designed primarily to percolate water into the subsurface soils within ten feet of foundations or near slopes. Due to the physical characteristics of the site earth materials, infiltration of waters into the subsurface earth materials has a risk of adversely affecting below grade structures, building foundations and slabs, hardscape improvements and slope stability. From a geotechnical viewpoint surface drainage should be directed to the street. The WQMP requirement shall be addressed by the Civil Engineer. 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: Foundation excavations for all structures • Drainage and rock placement behind retaining walls • Backfill compaction behind retaining walls ___Exterior_andinteriorslab_subgrade_compaction testing and moisture_ conditioning_ prior_ to_placement--- of placement—of the capillary break or waste slab • Compaction of exterior and interior utility trenches COAST GEOTECHNICAL, INC. Mr. Gary Uecker 9 W.O. 544317-03 Rough Grade Compaction Report July 1, 2019 Hardscape subgrade It is the responsibility of the developer to schedule the required observations and testing. REGULATORY COMPLLANCE 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 Code 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 made 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-Tamg Chen RCE 54011 `r c" �\ lI No b40 -1I_ ` ,r, z;auly ,, N COAST GEOTECHNICAL, INC. Mr. Gary Uecker to W.O. 544317-03 Rough Grade Compaction Report July 1. 2019 COMPACTION TEST RESULTS TABLE 1 1 Pad Area 3.54.0 11.6 113.5 I 90.8 6/18/19 2 Pad Area 3.54.0 10.1 113.8 I 91.0 6/18/19 3 Pad Area 2.53.0 12.1 113.3 1 90.6 6/18/19 4 Pad Area 2.53.0 9.9 113.9 I 91.1 6/18/19 5 Pad Area 1.01.5 11.2 113.5 I 90.8 6/19/19 6 Pad Area 4.04.5 8.9 114.0 I 91.2 6/19/19 7 Pad Area 4.04.5 8.4 114.6 I 91.7 6/19/19 8 Rear Deck Footing Area 6.06.5 15.1 100.5 rV 91.4 6/19/19 9 Pad Area 0.51.0 9.0 117.4 I 93.9 6/19/19 10 Pad Area 3.03.5 12.5 117.0 1 93.6 6/19/19 11 Rear Slope Area 5.05.5 15.4 107.1 II 90.8 6/20/19 12 Rear Slope Area 4.55.0 16.2 108.3 II 91.8 6/20/19 13 Rear Slope Area 4.55.0 15.9 107.9 II 91.4 6/20/19 14 Pad Area 3.03.5 16.9 108.2 II 91.7 6/20/19 15 Pad Area 2.53.0 10.1 115.6 I 92.8 6/20/19 16 Pad Area 2.02.5 15.2 109.4 H 92.7 6/21/19 17 Pad Area 4.04.5 10.5 113.9 I 91.1 6/24/19 18 Pad Area 2.53.0 10.0 113.5 1 90.8 6/24/19 19 Pad Area 1.52.0 9.8 114.9 I 91.9 6/24/19 COAST GEOTECHNICAL, INC. Mr. Gary Uecker ] 1 W.O. 544317-03 Rough Grade Compaction Report July 1, 2019 20 Pad Area F.G. 10.3 115.7 III 91.1 6/26/19 21 Pad Area F.G. 12.5 115.4 III 90.9 6/26/19 22 Pad Area F.G. 10.0 117.7 III 92.7 6/26/19 F.G.: Finish Grade COMPACTION TEST LOCATIONS 'ridII�LL� 7 Pescador Drive 3.20 �9 "o w Sao v , WO N L QV �18 it 4Mrm 3z`4? 0. r z 7 *22 Rough Grade Compaction Report Scale: V'= 20' Compaction Fest Location of 1 Work Order 544317-03 C 'f Plate No. 1 wport Beach, ali orma COAST GEOTECHNICAL, INC.