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HomeMy WebLinkAboutX2021-2460 - Soils (3)COAST GEOTECHNICAL, INC. 1200 West Commonwealth, Fullerton, CA 92833 Phone: (714) 870-1211 Fax: (714) 870-1222 Email: conteeotecna.sbcelobal.net June 16, 2022 W.O. 607320-03 Mr. and Mrs. Damien Burke 29 Inverness Lane Newport Beach, CA 92660 References: Subject: Rough Grade Compaction Report for Proposed New Residence at 29 Inverness Lane, Newport Beach, California Geotechnical and Geologic Investigation of Proposed New Residence at 29 Inverness Lane, Newport Beach, California; by COAST GEOTECFINICAL, Inc., W.O. 607320-01, dated February 19, 2021. 2. Addendum Report, Proposed Retaining Walls, New Residence at 29 Inverness Lane, Newport Beach, California; by COAST GEOTECBNICAL, Inc., W.O. 607320-02, dated September 2, 2021. Dear Mr. and Mrs. Burke: Forwarded herewith is the rough grade compaction report for the subject site. Our observations and testing were performed periodically, as requested. The grading operation for the residential development consisted of backfill of an existing pool, grading the residential pad and hardscape areas to provide adequate support and improve soil conditions, as well as removal of roots and vegetation. The grading operation was conducted from February 16, 2022 through February 28, 2022. The rest of the grading operation will be addressed in the final soils report. POOL BACKFILL The pool depth ranged from about six to ten feet deep with the deep -end at the southeast end of the pool. The entire pool shell was removed from the site prior to backfill. The bottom of the pool area was moisture conditioned and compacted to a minimum of 90% relative compaction prior to fill placement. Subsequent fills were placed in six to eight inch loose lifts, moisture conditioned as needed, and compacted to a minimum of 90% relative compaction by track rolling. This process was followed until near bottom of over -excavation for the building pad. Compaction test locations are shown on the attached, Plate 1. Equipment used for the compaction of fill soils consisted of a Cat 973C track loader. Soils were moisture conditioned by a water hose, when needed. Earthwork was by Tight Quarters. PLACEMENT OF FILL Compacted fill material was placed to provide adequate support for the proposed structure. COAST GEOTECHNICAL, INC. Mr. and Mrs. Burke 2 W.O. 607320-03 Rough Grade Comnaction Renort June 16, 2022 The over -excavation of the building pad area extended into competent fill material. The depth of over -excavation was about two to three feet below original grade. The exposed surface was scarified, moisture conditioned as needed, and compacted to a minimum of 90% relative compaction. Subsequent fills were placed in six to eight inch loose lifts, moisture conditioned as needed, and compacted to a minimum of 90% relative compaction by track rolling. Import soils were used to reach finish grades. The finish grade elevations are near to approximately six inches below original grade. Limits of grading are shown on the attached Plate 1. Equipment used for the compaction of fill soils consisted of a Cat 973C track loader and Kubota SVL 95 rubber track loader. Soils were moisture conditioned by a water hose, when needed. Earthwork was by Tight Quarters. 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 Soil Type Classification Optimum Moisture, % Max. Dry Density, lbs/ft3 I Light Brown to Light Tan Clayey 12.5 120.0 Silty Fine Grained Sand Light Brown to Light Tan Slightly II Clayey Silty Fine Grained Sand 12.5 120.0 With Portland Cement Import - Light Brown Tan Brown III Silty Fine Grained Sand with 9.0 118.0 Portland cement 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 method. The test results are summarized in Table 1. The approximate test locations are shown on Plate 1. FOUNDATIONS FOR RESIDENCE AND POOL The residence and pool will require deepened foundations to derive support from competent bedrock and or to comply with foundation setbacks from a descending slope. A caisson and grade beam system is typically utilized. The caissons shall be a minimum of two feet in diameter and shall extend a minimum of five feet into competent bedrock. The caissons may be designed as friction piles utilizing a skin friction value of 500 psf for competent bedrock. The point of fixity may be taken at five feet below ground surface. COAST GEOTECHNICAL, INC. Mr. and Mrs. Burke 3 W.O. 607320-03 Rough Grade Compaction Report June 16, 2022 Spacing of drilled caisson should not be closer than 3D, center to center, where D is the pile diameter. This value is for dead plus live load and may be increased by 1/3 for total including seismic and wind loads where allowed by code. Drilling of caissons shall be observed and logged by the project geologist to verify embedment requirements into competent bedrock and observed and approved by the soils engineer to verify compliance with project geotechnical requirements. Dependent on conditions exposed the project geologist or soils engineer may require the foundation excavations to be extended deeper. FOUNDATIONS FOR SECONDARY STRUCTURES Secondary structures, approved by the geotechnical engineer, may be supported by compacted fills or competent native soils. These improvements may be supported by continuous spread footings or isolated pads placed a minimum of 24 inches below lowest adjacent grade and bearing into compacted fill or native soil, but not a combination of the two. Foundations complying with these recommendations may utilize an allowable bearing value of 1,500 psf. This value is for dead plus live load and may be increased by 1/3 for total including seismic and wind load where allowed by code. Where isolated pads are utilized they shall be tied in two directions into adjacent continuous or pad footings with designed grade beams. Where conventional foundations must be deepened, to comply with embedment requirements, the foundation excavation may be backfilled up to the design footing bottom elevation with three sack slurry. The structural engineer shall provide a detail showing any needed reinforcement between the slurry and foundation concrete. Minimum geotechnical reinforcement of foundations shall be four 45 bars, two top and two bottom. Structural design may require additional reinforcement. Footings excavations are to be observed by a representative of COAST GEOTECHNICAL, Inc., to verify compliance with geotechnical and structural requirements. 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 for compacted fill. Passive pressure on the face of footings may also be used to resist lateral forces. A passive pressure of zero (0) at the surface of finished grade, increasing at the rate of 300 pounds per square foot of depth to a maximum value of 3,000 pounds per square foot, may be used for compacted fill and native soil. For bedrock, a passive pressure of zero (0) at the contact, increasing at the rate of 450 pounds per square foot of depth to a maximum value of 6,000 pounds per square foot may be used. 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. Passive pressure shall be ignored in the creep zone. COAST GEOTECHNICAL, INC. Mr. and Mrs. Burke 4 W.O. 607320-03 Rough Grade Compaction Report June 16, 2022 CREEPLOAD Creep loads may impact proposed site improvements. Proposed foundations and site improvements located within fifteen feet of a top of slope or located on a 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. LATERAL FILL EXTENSION (LFE) Lateral fill extension is a condition that may occur as a result of soil expansion, soil creep, settlement and other factors that causes horizontal and to a lesser extent vertical movement and tilt between site improvements. Typically site improvements near the top of slope have the potential to exhibit a greater degree of movement (on the order of a few inches), while improvements located away from a top of slope area may show a separation of a one half -inch (between the garage and driveway/hardscape slab.) FOUNDATION SLOPE SETBACK Based on the CBC, foundations shall maintain a setback as measured horizontally from the bottom outside footing edge to a competent slope surface of H/3 where H is the slope height. Based on a slope height of thirty five feet an H/3 slope setback of twelve feet is recommended. EXPANSIVE SOILS Results of expansion tests indicate that the near surface soils have a low to medium expansion potential. The medium recommendations on the accompanying "Expansive Soil Recommendations", Plate A, may be utilized in design of hardscape. SETTLEMENT The maximum total post -construction and differential settlements are anticipated to be less than one-half inch, measured between adjacent structural elements over a distance of forty feet for improvements supported by compacted fill. The maximum total post -construction and differential settlements are anticipated to be less than one -quarter inch, measured between adjacent structural elements over a distance of forty feet for improvements supported by foundations bearing into bedrock. SEISMIC DESIGN Based on the 2019 CBC the following seismic design parameters are provided. These seismic design values were determined utilizing latitude 33.6245911 and longitude-117.868679 and calculations from the USGS ground motion parameter calculator. Based on near surface bedrock a site class C was assigned to site earth materials. • Site Class = C • Mapped 0.2 Second Spectral Response Acceleration, Ss = 1.326g • Mapped One Second Spectral Response Acceleration S, = 0.471 g • Site Coefficient from Table 1613A.3.3(1), Fa = 1.2 • Site Coefficient from Table 1613A.3.3(2), Fv = 1.5 COAST GEOTECHNICAL, INC. Mr. and Mrs. Burke 5 W.O. 607320-03 Rough Grade Compaction Report June 16, 2022 • Maximum Design Spectral Response Acceleration for short period, Sms = 1.591g • Maximum Design Spectral Response Acceleration for one -second period, Sm, = 0.707g • 5% Design Spectral Response Acceleration for short period, Sos=1.061g • 5% Design Spectral Response Acceleration for one -second period, SDI = 0.47lg SOLUBLE SULFATES A chemical analysis of typical near surface earth materials for soluble sulfates showed a sulfate content of 225 ppm. Based on the current CBC and Table 4.3.1 of ACI 318 this is a moderate exposure to sulfate corrosion. Type II cement, with 4,000 psi and a water cement ratio of 0.50 is required per the referenced table. Structural requirements may dictate a higher strength concrete. RETAINING WALLS Unrestrained retaining walls may be founded in competent native soils, compacted fill or bedrock utilizing previously stated bearing values. Walls retaining drained earth under static loading may be designed for the following: Surface Slope of Retained Material Horizontal to Vertical Equivalent Fluid Pressure Pounds per Cubic Foot Level 39.9 5 to 1 47.3 4 to 1 49.9 3 to 1 55.7 2 to 1 86.7 Calculations for the stated equivalent fluid pressures are based on the Coulomb theory. The point of resultant force is at H/3 above the base of the retaining wall, where H is the wall height. All retaining structures should include appropriate allowances for anticipated surcharge loading, where applicable. Retaining walls with an ascending slope condition shall include a minimum one -foot free board and concrete swale in their design. The provided design is based on the use of select very low expansive granular earth materials as backfills. The structural engineer shall designate this on his plans. Onsite earth materials that exhibit the required characteristics may be used as backfills. Footing excavations require observation and approval by COAST GEOTECHNICAL, Inc. SEISNIIC DESIGN VALUE Code requires that retaining walls with more than six feet of backfill be designed for seismic loads. For a retaining wall under earthquake loading the designed equivalent fluid pressure is sensitive to the ground motion value applied to analysis. Our understanding is that the current reviewer for the City of Newport Beach utilizes Sns for the ground motion and allows the consulting engineer to utilize his allowed reduction to determine the seismic coefficient Kh. COAST GEOTECHNICAL, INC. Mr. and Mrs. Burke 6 W.O. 607320-03 Roueh Grade Compaction Report June 16 2022 For unrestrained conditions a Kh value of 0.212 was determined. Use of this value in a simplified analysis method allowed by the reviewer, determines that a seismic load of 19.1 pcf should be utilized by the structural engineer. For restrained conditions a Kh value of 0.361 was determined. Use of this value in a simplified analysis method, determines that a seismic load of 32.5 pcf should be utilized by the structural engineer. WATERPROOFING Waterproofing of any proposed retaining walls is highly advised. The geotechnical consultant is only responsible for identification of adverse moisture conditions, which could impact retaining structures and the basement of the structure. The waterproofing for the retaining walls and basement slab should be designed, and field inspected during construction accordingly, by a qualified person. Waterproofing design is not within the expertise or work scope of the soils engineer or geologist. A H 17.7_11►F.9 Subdrain systems shall be installed behind retaining walls and beneath basement slabs 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. and the Civil Engineer. RETAINING WALL BACKFILL Retaining wall backfills shall consist of select very low expansive granular earth materials, or gravels. On -site soil may be used as a soil cap. If imported gravels are used as backfill material, the gravels shall be separated from on -site soils with filter cloth. Gravel backfill material shall be heavily watered and compacted as they are placed. A soil cap, consisting of on -site soils or similar material, shall be placed over any gravel backfill and separated by filter cloth from the underlying material. The soil cap shall be a minimum of three feet in thickness or one foot below footing bottoms, whichever is deeper. Soil cap soils shall be placed in six to eight inch loose lifts, moisture conditioned as needed, and compacted to a minimum of 90% relative compaction. 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 ninety percent relative compaction. Backfills require testing at two -foot vertical intervals during placement. COAST GEOTECHNICAL, INC. Mr. and Mrs. Burke 7 W.O. 607320-03 Rough Grade Compaction Report June 16, 2022 Compaction of backfills requires observation and approval by COAST GEOTECHNICAL, Inc. during the backfill operation. FLOOR SLABS Floor slabs shall be designed as structural slabs. Subgrade soils shall exhibit a minimum relative compaction of 90% to the depth determined by the geotechnical engineer. 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. COAST GEOTECHNICAL, Inc. will need to verify adequate mitigation. Prior to placement of the capillary break and or vapor barrier COAST GEOTECHNICAL, Inc., shall test the slab subgrade soils for moisture content. If the subgrade soils do not exhibit the recommendations on Plate A they shall be moisture conditioned to the required depth and content. The capillary break material shall comply with the requirements of the local jurisdiction 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 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 may be in contact with the slab bottom. POOL/SPA DESIGN RECOMMENDATIONS The proposed infinity edge pool and spa shall be designed as free standing and supported by drilled cast in place piles bearing into bedrock to minimize settlement and to provide the required H/3 setback. Pool walls shall be designed to support the water, having a density of 62.4 pounds per cubic foot without bearing from adjacent earth material. The walls should be able to support the adjacent earth material when the pool is empty. The earth pressure may be calculated as an equivalent fluid pressure of 100 pounds per cubic foot for level backfill, plus the lateral pressure due to any superimposed surcharge when the pool is empty. Expansion joints shall be placed between the pool and deck. COAST GEOTECHNICAL, INC. Mr. and Mrs. Burke 8 W.O. 607320-03 Rough Grade Compaction Report June 16, 2022 All pool utility lines shall be backfilled with soils compacted to a minimum of 90% relative compaction. Where pool lines are sensitive to the use of compaction equipment the trenches shall be backfilled with one sack slurry. COAST GEOTECHNICAL, Inc. shall verify the backfill of all trenches. Pool decking shall be cast free of the swimming pool structure and access openings. The free space shall be filled with flexible water stop materials. The client is advised that due to the expansive nature of site soils that some horizontal and vertical movement between the pool and pool decking will occur over time. The pool foundation excavation shall be observed and approved by COAST GEOTECHNICAL, Inc. prior to the placement of reinforcement. These recommendations are subject to change based on the review of pool plans. All pool/spa utility lines shall be backfilled with soils compacted to a minimum of 90% relative compaction. Where pool lines are sensitive to the use of compaction equipment the trenches shall be backfilled with one sack slurry. COAST GEOTECHNICAL, Inc. shall verify the backfill of all trenches. Drilling of piles and excavation of footings are to be observed by a representative of COAST GEOTECHNICAL, Inc., to verify compliance with geotechnical and structural requirements. SCREEN WALLS Screen walls shall be designed and constructed to minimize the effects of expansive soils, slope creep, and lateral lot extension. The following recommendations shall be utilized in design. Walls on the slope and within fifteen feet of the top of slope shall be designed to resist expansive soils and soil creep. We recommend drilled piles placed a minimum of five feet into bedrock and maintain a setback of twelve feet from the slope face. A grade beam shall interconnect the piles. The piles may be designed for a skin friction value provided under the foundation section of this report. The wall foundations shall be designed to resist a creep force of 1,000 pounds per foot of depth for the upper three feet of slope material. Passive pressure shall be ignored in the creep zone. • All site walls shall be properly jointed and shall utilize foundations placed a minimum of 24" below grade. • Decorative walls shall be designed to accommodate potential movement. HARDSCAPESLABS Hardscape slab subgrade areas shall exhibit a minimum of 90% relative compaction and a moisture content of 3-4% over optimum, to a depth of at least three feet. Deeper removal, moisture conditioning and compaction may be required if unacceptable conditions are encountered. These areas require testing just prior to placing concrete. COAST GEOTECHNICAL, INC. Mr. and Mrs. Burke 9 W.O. 607320-03 Roueh Grade Compaction Report June 16, 2022 Exterior hardscape slabs will be subject to stress from volume changes in subgrade soils, which may lead to cracking. The followings recommendations will minimize cracking and offsets, but will not eliminate concrete cracks. Exterior hardscape shall be five inches actual thickness with # 3 bars at twelve inches on center each way. The placed concrete shall be placed, cured, jointed and sawcut in accordance with appropriate ACI and or PCA recommendations. Doweling slabs to perimeter footings can mitigate movement of slabs adjacent to structures. 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-off wall to the same depth and containing the same reinforcement as exterior footings is recommended. Reinforcement adopted for the main structure may be applied to the appurtenances. As an alternative to rigid hardscape or brickwork, flexible pavers maybe utilized. UTILITY LINE BACKILLS 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. 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. The 2019 CBC recommends 5% slope away from structures for landscape areas and 2% slope away for hardscape areas, within ten feet of a residence. Minimum drainage shall be one percent for hardscape areas and two percent for landscape areas for all other areas. We do not recommend the use of infiltration best management practice (BMP); such as, bottomless trench drains, infiltration trenches, infiltration basins, dry wells, permeable pavements or similar systems designed primarily to percolate water into the subsurface soils. 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, and hardscape improvements. From a geotechnical viewpoint surface drainage should be directed to the street. COAST GEOTECHNICAL, INC. Mr. and Mrs. Burke 10 W.O. 607320-03 Rough Grade Compaction Report June 16, 2022 Fossil filtration or bio-retention planters are currently being employed in the Newport area with similar soil conditions instead of bottomless infiltration trenches. 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: • Excavation of pile foundation system • Backfill and compaction of interior slab areas • Backfill of interior trenches • Backfill of exterior utility trenches • Hardscape subgrade 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 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. 3� �_'� Ming-Tarng Chen RCE 54011 COAST GEOTECHNICAL, INC. Mr. and Mrs. Burke 11 W.O. 607320-03 Rough Grade Compaction Report June 16, 2022 COMPACTION TEST RESULTS TABLE 1 Not Location Below Proposed Grade (ft) Moisture 'Content % Dry Unit Weight (lbs/ft) Toe Relative Compaction % Date', 1 Pool Backfill 9.5-1.0 17.5 108.6 I 90.5 2/16/22 2 Pool Backfill 8.0-8.5 16.1 108.8 I 90.7 2116/22 3 Sewer Backfill 4.0-4.5 14.9 109.2 I 91.0 2/16/22 4 Pool Backfill 5.0-5.5 15.2 109.0 I 90.8 2/16/22 5 Pool Backfill 4.0-4.5 14.3 109.3 I 91.1 2/16/22 6 Sewer Backfill 2.5-3.0 15.1 109.1 I 90.9 2/17/22 7 Pool Backfill 2.5-3.0 14.7 109.6 I 91.3 2/17/22 8 Pad Area 2.0-2.5 16.3 108.8 I 90.7 2/17/22 9 Pad Area 2.0-2.5 15.8 108.6 I 90.5 2/17/22 10 Pad Area 2.0-2.5 16.5 108.4 I 90.3 2/17/22 11 Pad Area 1.5-2.0 15.1 109.7 II 91.4 2/18/22 12 Pad Area 1.5-2.0 15.7 109.3 II 91.1 2/18/22 13 Pad Area 2.0-2.5 9.9 110.0 II 91.7 2/22/22 14 Pad Area 1.0-1.5 12.5 109.7 II 91.4 2/22/22 15 Pad Area 0.5-1.0 14.0 109.2 II 91.0 2/22/22 16 Pad Area 0.0-0.5 11.2 107.5 1II 91.1 2/24/22 17 Pad Area 0.0-0.5 12.1 109.2 III 92.5 2/24/22 18 Hardscape Area 2.0-2.5 13.8 108.7 II 90.6 2/25/22 19 Pad Area F.G. 12.0 107.2 III 90.9 2/28/22 20 Pad Area 0.0-0.5 11.4 107.6 II1 91.2 2/28/22 21 Pad Area 0.0-0.5 12.4 107.4 III 91.0 2/28/22 22 Pad Area F.G. 11.7 107.0 III 90.7 2/28/22 F.G.- Finish Grade FR MED BY CIVIL ENSIA.PNZ GINEER L 11 TBftO f�L150 VIEIEJO C. 93656 T1411J0.]455 COMPACTION TEST LOCATIONS Scale: 1'! z 30' Geotechnical Engineering Investigation I Work Order 607320 29 Inverness Lane ✓port Beach, California I Plate No. 1 COAST GEOTECHNICAL, INC.