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HomeMy WebLinkAboutMS 2022-0003; 1098 MAGNOLIA AVE; SITE INVESTIGATION FOR PROPOSED RESIDENTIAL BUILDING SITE NEXT TO 1098 MAGNOLIA AVE; 2023-01-12January 12, 2023 Mehrdad Dokhanchy 1098 Magnolia Avenue Carlsbad, California 92008 SUBJECT: Dear Mr. Dokhanchy: SCOPE File No. 1106F6-21 SITE INSPECTION (Original Report July 19, 2022) Proposed Residential Building Site Next to 1098 Magnolia Avenue City of Carlsbad PD 2021-0046 DWG 555-6A P.O. Box 1195 Lakeside, California 92040 (619) 443-0060 In accordance with your request, a Site Inspection has been performed at the subject site. The purpose of this investigation was to examine existing site conditions and provide engineering recommendations for the proposed two story single family residence with raised floor construction and attached garage. If project details vary significantly from those described, Soil Testers should be notified prior to final submittal for revision and possible revision of the recommendations presented herein. This report is issued with the understanding that it is the responsibility of the owner or the owner's representative to ensure that the information and recommendations contained herein are brought to the attention of the architect and engineer for the project and incorporated into the plans, and the necessary steps are taken to see that the contractor and subcontractors carry out such recommendations in the field. We conclude that the proposed development of the site is feasible from a geotechnical standpoint provided the recommendations in this report are incorporated into the design and construction of the project. The proposed grading and development should have no geologic or geotechnical impact on adjacent properties or improvements. 1 Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 VICINITY MAP e 9 Library Learning Cen er y JU ~µclC..t:: .::.UiUUUll · 9 9 9 t,_ Carlsbad Solar $ -l'~e 9 ~ orth Count Little Free Llbr ry 1}3201-3365 ~es'-"'~' Darren Machulsky \ 0 Pr1me Proper • T Inspections 9 :J Senior Center :arlsbad 1gh9 I St P1rking Y' rlarding S Par~ing Harding G rdens Apartme s q 9 Chase Field "'&~ ~0-? -5> Casa MontcSSOfl O n~\<:-' de Carlsbad Y , ~ .. Chestnut Ave ft Tandy Blank Garage T Te~ra'"1 • do,e-1 B Hyland Inn I Ho· se San Diego Real Estate ~ Near Legoland T H•(29s1 2-Gtarnotef 9 9 Cinn-mon Ap nments c; ~ Meantime• Wellness Center 9 cansbad Manufact red Home Builders q Tavarua Senior Apartmen s 9 ft Mindful Movers ,1098 Magnolia Ave. T North County Carlsbad, CA 92008 B B ookkeeptng ft Serv1cesT B 9 Cindy Family Daycare The Screen Company Flemings Auto Detail q Magnolia two Magnolia anm Apar ments Bluewater TIie q Th~ Village Apanmems 9 SHIPGDsq l Hot List Top Business B1oke1s ,n San Diego 9 "~~ ~ 'l\o\ y ~" JeffersonO Eler en ary School Y Days Inn by Q Wyndham Carlsbad B i!.!~~~:1 q Ye Olde G rage Sale 9 Jus11n s Spa Repair Village Kitchen & Pie Shoppe i:..,~•t~ :"\•$ q St Patr1ck Ca holic Church vonsq 9 q AdesseP.rt Ed,vards Tax & Financ,al Services 9 9 e El AV Ch Carlsb, The property is generally level, with elevations ranging from 83 to 85 feet mean sea level (msl). REGIONAL and SITE GEOLOGY The subject property is underlain by Old Paralic Deposits (Qop2-4). The Old Paralic Deposits, Units 2-4, are late to middle Pleistocene in age. These sedimentary rock deposits are poorly sorted, moderately permeable, reddish brown, interfingered strandline, beach, estuarine and colluvial deposits composed of siltstone, sandstone and conglomerate. Generally, these deposits possess moderate to firm cementation, and good to very good bearing strength values. 2 Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 REGIONAL AND LOCAL SEISMICITY San Diego's tectonic setting includes north and northwest striking fault zones, the most prominent and active of which is the Newport-Inglewood-Rose Canyon Fault Zone. Activity along active faults within this fault zone present the most immediate seismic hazards to San Diego. Other Fault zones including the Elsinore fault zone lie in eastern and northern San Diego County. Fault rupture hazard would affect a property if an active fault trace or traces traverse the property. The subject property is not within an Alquist-Priolo Earthquake Fault Zone (Special Studies Zone). The nearest active fault segment is the offshore Oceanside section within the active Newport-Inglewood-Rose Canyon Fault Zone, 4.8 miles southwest of the site. This section is considered fault type A, well constrained, latest Quaternary in age, with right-lateral slip of 1 to 5 rrim/yr. The site is approximately 24 miles southwest of faults within the active Elsinore Fault Zone (Temecula section). Even though direct ground rupture from faulting directly underneath the subject property is not likely, the property may be subjected to considerable ground acceleration and shaking from an earthquake event along nearby faults. The intensity of ground shaking is dependent on distance from faults, earthquake magnitude and duration, and seismic characteristics of foundation soils and bedrock. The effective ground acceleration at the site is associated with the part of significant ground motion, which contains repetitive strong-energy shaking, and which may produce structural deformation. As such, the effective or "free field" ground acceleration is referred to as the Repeatable High Ground Acceleration (RHGA). It has been determined by Ploessel and Slosson (1974) that the RHGA is approximately equal to 65 percent of the Peak Ground Acceleration for earthquakes occurring within 20 miles of a site. Based on the above, the calculated Credible RHGA at the site is 0.36g. The current California Building Code includes parameters for assessing the effects of seismic shaking and ground acceleration on structures. Below we provide a table summarizing near-source factors and seismic coefficients, which are used by structural engineers in building and foundation design. We have utilized a web-based tool (https://asce7hazardtool.online/) to derive seismic factors for site seismicity. 3 Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 Table 1. Site Seismic Parameters from asce7hazardtool.online Parameters Values Site Class D Mapped Short Period Spectral Acceleration, Ss 1.2 Mapped One-Second Period Spectral Acceleration, S 1 0.38 Short Period Spectral Acceleration Adjusted For Site Class, SMS 1.44 One-Second Period Spectral Acceleration Adjusted For Site Class, SMI 0.96 Design Short Period Spectral Acceleration, SDS 0.96 Design One-Second Period Spectral Acceleration, SD 1 0.64 Modified Peak Ground Acceleration, PGAm 0.56g -LIQUEFACTION AND LATERAL SPREADING HAZARD The subject property is underlain by dense to very dense, well indurated formational sedimentary marine and nearshore sandstones and claystones and siltstones of the Old Paralics Formation, at shallow depths. In situ density and particle size characteristics of these sedimentary rocks indicate negligible risk of liquefaction or lateral spreading during major seismic events on nearby active earthquake faults. LANDSLIDE HAZARDS There are no known active or ancient landslides underlying the subject property. The property is within an extensively graded, well developed suburban residential area. TSUNAMIS AND SEICHES Tsunami indundation maps for emergency planning, compiled by the California Geological Survey, show that the property does not lie within a projected inundation area. According to the CGS' website, the largest recorded tsunami to hit San Diego was 3.6 meters (approximately 10 feet) in the year 1856, from a seismic event in Japan. A seiche is a wave generated in a standing body of water by an earthquake or a landslide. Agua Hedionda, a natural estuary bay, lies some 0.60 miles to the south. It is unlikely that 4 Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 a seiche, locally generated by an earthquake or landslide, in this body of water, would affect the property. FLOODING The site is in an area of minimal flooding as defined by FEMA (map no. 06073C0764H, dated 12/20/2019.) SITE SUIT ABILITY The subject property does not lie within a state or City -designated Earthquake Fault zone, and there is no evidence of active or potentially active fault traces underlying the site. The site is developable from a geologic standpoint. Development will not result in undue risk from geologic and erosional forces and flood hazards. FIELD INSPECTION In order to accomplish this purpose, a representative of this firm visited the site, reviewed the topography and site conditions and visually and texturally classified the surface and near surface soils. Representative samples of the on-site soils were obtained from 2 test explorations utilizing a mini-ex approximately 4 feet in depth and tested for density, shear strength and expansive characteristics. SITE CONDITIONS The subject site is located on the northerly side of Magnolia A venue. The site is a relatively level vacant lot with a wood fence along the north and west property lines. A hedge lines the front of the property and ground cover lines the driveway to the east. Neighboring properties are occupied by single family residential structures. Fill materials were not encountered, and compressible native soils were encountered to a depth of approximately 3 to 4 feet during the course of this inspection. SOIL CONDITIONS Soils encountered in the test explorations were native soils consisting of loose to firm, brown, moist, fine, silty sands to the bottom of the explorations at approximately 4 feet. The soils we encountered were not considered to be detrimentally expansive with respect to change in volume with change in moisture content. 5 Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 CONCLUSIONS AND RECOMMENDATIONS 1. A representative sample of the foundation soil was remolded to 90% of maximum dry density. Based on the following test results, a safe allowable bearing value of at least 2000 pounds per square foot for 12 inch deep footings may be used in designing the foundations and slab for the proposed structures. This value may be increased by one third for wind and/or seismic loading. This value may be increased by 20 percent for each additional foot of depth and or width to a maximum of 3 times the designated value. Maximum Dry Density Optimum Moisture Angle of internal friction Cohesion Unit weight Expansion Index 131.9 pcf 8.6% 30° 164 psf 120.2 pcf 21 2. The soils we encountered were considered to be Low-Expansive Index (EI), (with the value ranging from 21 to 50) with respect to change in volume along with change in moisture content. For the remaining indexes: Low (EI=21-50), medium (EI=51-90), high (EI=91-130), and very high (EI> 130). 3. Lateral resistance to horizontal movement may be provided by the soil passive pressure and friction of concrete to soil. An allowable passive pressure of 250 pounds per square foot per foot of depth may be used. A coefficient of friction of 0.35 is recommended. The soils passive pressure may be increased by 1/3 for wind and seismic loading. 4. Total and differential settlement is expected to be within industry adopted standards as long as the recommendations presented in our report are adhered to. Total settlement is expected to be less than 1 inch and differential settlement is expected to be less than 1/2 inch in 30 feet for foundations bearing on bedrock or the softer natural soils or fill soils. 5. The loose, compressible native soils we encountered should not be utilized to support the proposed new structure. They should be removed to competent native soils and recompacted to at least 90 percent of maximum dry density in accordance with the Grading Specifications in this report in order to provide adequate support for the proposed new structures. The recompaction should extend at least five feet outside the proposed building footprints. Organic materials and roots must be removed 6 Mehrdad Dokhanchy File No. l 106F6-21 January 12, 2023 from the soils before replacement. A representative of Soil Testers should be onsite to approve the removal of the loose soils prior to placement of fill soils. 6. Some of the loose soils may be removed from under the proposed house for the crawl space. As an alternative to the remove and recompact recommendations for the loose soils, the footing excavations for the raised floor area may be deepened a minimum of 12 inches into competent native soils. 7. Conventional spread footings founded a minimum of 12 inches below lowest adjacent grade and having a width determined by the allowable soil bearing value as detailed above are recommended for foundation support. Footing widths should be at least 12 inches for continuous footings and 24 inches for square footings due to practical considerations as well as Building Code requirements. These recommendations are based entirely upon the soil types and do not take into consideration the requirements of the proposed structure. 8. Reinforcing in footings should consist of at least one #4 steel bar placed continuously in the top and bottom of continuous footings regardless of structural requirements. Reinforcing for isolated footings is dictated by the structural requirements. These recommendations are based upon on the soil type encountered and do not take into consideration the proposed bearing load. 9. Concrete Slab-On-Grade, SOG, should be designed by the project's structural engineer based on anticipated loading conditions. We recommend that conventional reinforced concrete SOG for this project be founded on 4 inches of Class II Virgin Aggregate Base (with approximately 2% +/-over optimum moisture content and 90% compaction, relative to the lab maximum dry density, ASTM D 1557), overlying a 12 inch thick zone of adequately placed and compacted structural fill. The structural zone under the slab will be accomplished during the grading operation. We recommend that a moisture barrier be provided by a membrane, visqueen 10 mils in minimum thickness or equivalent, be placed at top of well compacted Class II Aggregate Base, then covered with 2 inches of moist clean sand having a minimum sand equivalent of 30 when tested in accordance with the American Society of Testing and Materials test method 'ASTM D2419. Floor slabs, as a minimum, should be 5 inches thick with #4 reinforcing steel at 16" on-center each way. Reinforcement should be placed at mid-height of the slab. The final slab thickness and reinforcement should be determined by the structural 7 Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 design engineer. Control joints should be provided m accordance with the recommendations of the structural design engineer. 10. The design civil engineer needs to look at the surrounding flat work concrete conditions. We recommend the soils under the flatwork be removed to competent native and recompacted during the grading operation. A minimum of 5. 5 inches with #3 rebar at 12 inches on center each way. Reinforcement should be placed at mid- height of the concrete. SITE EROSION CONTROL During the construction, surface water should be controlled via berms, gravel bags and/or sandbags, silt fence, straw wattles, siltation basins, while maintaining positive surface grades or other methods to avoid damage to the finish work or adjoining properties. All site entrances and exits must have coarse gravel or steel shaker plates to minimize offsite sediment tracking. Best management Practices (BMP's) must be used to protect storm drains and minimize pollution. The contractor should take measures to prevent erosion of graded areas until such time as permanent drainage and erosion control measures have been installed. After completion of grading, all excavated surfaces should exhibit positive drainage and eliminate areas where water might pond. SITE AND SURFACE DRAINAGE Drainage at the site should be directed away from foundations, collected and tight lined to appropriate discharge points. Consideration may be given to collecting roof drainage by eave gutters and directing it away from foundations via non-erosive devices. Water, either natural or from irrigation, should not be permitted to pond, saturate the surface soils or flow towards the foundation. Landscaping requiring a heavy irrigation schedule should not be planted adjacent to foundations or paved areas. The type of drainage issues found within the project and materials specified and used should be determined by the Engineer of Record. GROUNDWATER AND SURFACE WATERS There was no indication of a near-surface groundwater table within our exploratory trench or perched groundwater. Although groundwater is not expected to be a significant constraint to the proposed development, our experience indicates that near-surface groundwater conditions can develop in areas where no such groundwater conditions previously existed, especially in areas where a substantial increase in surface water infiltration results from landscape irrigation or unusually heavy precipitation. It is anticipated that site development will include appropriate drainage provisions for control 8 Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 and discharge of surface water runoff. The type of drainage issues found within the project and materials specified and used should be determined by the Civil Engineer. The type of plants and soil specified along with proper irrigation used should be determined by the Landscape Architect. The following grading specifications should be utilized if grading is proposed. RECOMMENDED GRADING SPECIFICATIONS For Proposed Residential Building Site Next to 1098 Magnolia Avenue City of Carlsbad GENERAL: Soil Testers and 'Engineer' are synonymous hereinafter and shall be employed to inspect and test earthwork in accordance with these specifications, the accepted plans, and the requirements of any jurisdictive governmental agencies. They are to be allowed adequate access so that the inspections and tests may be performed. The Engineer shall be apprised of schedules and any unforeseen soil conditions. Substandard conditions or workmanship, inadequate compaction, adverse weather, or deviation from the lines and grades shown on the plans, etc., shall be cause for the engineer to either stop construction until the conditions are corrected or recommend rejection of the work. Refusal to comply with these specifications or the recommendations and/or interpretations of the engineer will be cause for the engineer and/ or his representative to immediately terminate his services. A pre-construction meeting or conference with the developer, contractor, civil engineer, soil engineer, and the agency inspector in attendance should be held at the site prior to the beginning of the grading operations. Special soil handling requirements can be discussed at that time. Grading of the site should commence with the removal of all vegetation and existing improvements from the area to be graded. Deleterious material and debris such as broken asphalt and concrete, underground pipe materials, wires, trash, etc. if encountered, should be exported from the site and should not be mixed with the fill soils. Abandoned foundations and buried septic tanks or cisterns (if encountered) should be removed and the subsequent depressions and /or trenches should be filled with properly compacted materials as part of the remedial grading. All fill and backfill soils should be placed in horizontal loose layers approximately 8 inches 9 Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 thick, moisture conditioned to a water content of one to three percent above optimum moisture content, and compacted to at least 90 percent relative compaction, as determined by ASTM Test Method D 1557-00. The excavation bottom should then be scarified to a depth of approximately 6 to 8 inches, moisture-conditioned to 1 to 3 percent above optimum moisture content, and re- compacted to a minimum relative compaction of 90 percent in accordance with ASTM D 1556-00 or D6938-17.ael. Excavated sandy or clayey soils should then be uniformly moisture conditioned at above optimum moisture content, placed in 8-inch-thick loose layers and compacted to a relative compaction of at least 90 percent. Import fill soil, if required, should consist of granular materials with low expansion potential (EI less than 50 or stated by the soil engineer) and should be compacted as indicated herein. Soil Testers should be notified of the import source and should perform laboratory testing of the soil prior to its arrival at the site to determine its suitability as fill material. Deviations from the recommendations of the Soil Report, from the plans, or from these Specifications must be approved in writing by the owner and the contractor and endorsed by the engineer. SOIL TEST METHODS: Maximum Density & Opt Moisture Density of Soil In-Place --ASTM D1557-70 --ASTM D1556, D2922 and D3017 Soil Expansion Shear Strength Gradation & Grain Size Capillary Moisture Tension Organic Content --UBC STANDARD 29-2 --ASTM D3080-72 --ASTM Dl 140-71 --ASTM D2325-68 --% Weight loss after heating for 24 hours at 300° F and after deducting soil moisture. LIMITING SOIL CONDITIONS: Minimum Compaction Expansive Soils Insufficient fines Oversized Particles 90% for 'disturbed' soils. (Existing fill, newly placed fill, plowed ground, etc.) 84 % for natural, undisturbed soils. 95% for pavement subgrade within 2' of finish grade and pavement base course. Expansion index exceeding 20 Less than 40% passing the #4 sieve. Rocks over 6" in diameter. 10 Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 PREPARATION OF AREAS TO RECEIVE FILL: Brush, trash, debris and detrimental soils shall be cleared from the areas to receive fill. Detrimental soils shall be removed to firm competent soil. Slopes exceeding 20% should be stepped uphill with benches 1 O' or greater in width. Scarify area to receive fill to 6" depth and compact. FILL MATERIAL shall not contain insufficient fines, oversized particles, or excessive organics. On-site disposition of oversized rock or expansive soils is to be at the written direction of the Engineer. Select fill shall be as specified by the engineer. All fills shall be compacted and tested. SUBDRAINS shall be installed if required by and as directed by and detailed by the engineer and shall be left operable and unobstructed. They shall consist of 3" plastic perforated pipe set in a minimum cover of 4" of filter rock in a 'vee' ditch to intercept and drain free ground from the mass fills. Perforated pipe shall be schedule 40, Poly-Vinyl-Chloride or Acrylonitrile Butadienne Styrene plastic. Rock filter material shall conform to the following gradation: Sieve size: ¾Passing: 3/4" 90-100 #4 25-50 #30 5-20 #200 0-7 Subdrains shall be set at a minimum gradient of 0.2% to drain by gravity. Drains found inoperable shall be excavated and replaced. CAPPING EXPANSIVE SOILS: If capping expansive soils with non-expansive soil to mitigate the expansive potential is used, the cap should be compacted, non-expansive, select soil placed for a minimum thickness 3' over the expansive soil and for a minimum distance of 8' beyond the exterior perimeter of the structure. Special precautions should be taken to ensure that the non-expansive soil remains uncontaminated and the minimum thickness and dimensions around the structure are maintained. The expansive soils underlying the cap of non-expansive cap should be pre-saturated to a depth of 3' to obtain a degree saturation exceeding 90% before any construction supported by the compacted cap. The non-expansive soil comprising the cap should conform to the following: Minimum Compaction Maximum Expansion Index Minimum Angle of Internal Friction Cohesion Intercept 11 90% 30 33 Deg 100 psf Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 UNFORESEEN CONDITIONS: Soil Testers assume no responsibility for conditions, which differ from those, described in the applicable current reports and documents for this property. Upon termination of the engineer's services for any reason, his fees up to the time of termination become due and payable. If it is necessary for the engineer to issue an unfavorable report concerning the work that he has been hired to test and inspect, the engineer shall not be held liable for any damages that might result from his 'unfavorable report'. If we can be of any further assistance, please do not hesitate to contact our office. This opportunity to be of service is sincerely appreciated. Plate I through III, Detail I and Standard Grading Guidelines are part of this report. Respectfully submitted, Bryan Miller-Hicks, CEG 1323, PG 4130 CCC/mlj 12 Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 REFERENCES 1. Kennedy, M.P., and Tan, S.S. 2007, Geologic Map of the Oceanside 30' x 60' Quadrangle, California, California Geological Survey. 2. Lindvall, S. C., and T. K. Rockwell (1995), Holocene activity of the Rose Canyon fault zone in San Diego,California ,JGeophys.Res., 100(B12),24,121-24,132. 3. (https://asce7hazardtool.online/), USGS Seismic Design Maps based on ASCE/SEI 7-22 and ASCE/SEI 7-22 Table 1.5-2 NO SCALE _y . 'i» '-...: . . -·~· ,. 7 ~ ~ . ' ., ~ •" .. , \.=<. "\.~ . ~ .~ '· .:;· \ '-:: " J ) ,., ~ \ -~ · .. ~ ) / fr,-..:-.. ·:-~. .,. ' . • -.• -.;"t/· .". / / , :A -~· . .,. ·, . ,-. ;.A . l-, '..i. -..-~--~ ·: J-t-',~ : ' . . \_--.:...... I -' ' ............ ;•;' ~~ ... • • ..• , -,· t' ~ ~ '·' I ~ lw~ ,I • 0 o'->"" ~r,..6~ [;iii EXPLORATION TRENCH LOCATION OF EXPLORATION TRENCHES JOB NO. BY PLATE I 1106F6-21 JJ 1-11-23 ~'0~ ~~ Mehrdad Dokhanchy Plate No. II EXPLORATION NUMBER 1 Date Logged: Date Reported: 09/22/2021 10/29/2021 D th U . fi d Cl . fi f ep ru 1e ass1 1ca 10ns 0 to 4' SM Brown, File No. 1106F6-21 January 12, 2023 Equipment Used: Backhoe Groundwater: Not Encountered 01 escnp 10n S 'ID . f S ·1 T 01 ype dry, loose, SILTY SANDS 1 (Native) moist, firm bottom of excavation Mehrdad Dokhanchy Plate No. III EXPLORATION NUMBER 2 Date Logged: Date Reported: 09/22/2021 10/29/2021 D h U .fi d Cl .fi ept m 1e ass1 1catlons 0 to 4' SM Brown, File No. 1106F6-21 January 12, 2023 Equipment Used: Backhoe Groundwater: Not Encountered S ·10 01 escnptlon S ·1 T 01 ype dry, loose, SILTY SANDS 1 (Native) moist, firm bottom of excavation = z 00 -~ :c 6: w a <.!)-f( z .,::: 0 0 LL = z 00 -~ I.. PER PLAN .. I NON-GRADED LOT * LOWEST ADJACENT GRADE OF STRUCTURAL FILL OR COMPACTED BASE -------b, ·p --------------..___ _____ ....,__ __________ ~ \.. PER PLAN .. I GRADED LOT 5" SLAB 2"TO4" SAND 4" TO 6" VIRGIN CLASS II BASE 5" SLAB 2" TO4" SAND 4" TO 6" VIRGIN CLASS II BASE * * LOWEST ADJACENT GRADE OF OUTSIDE GRADE OR COMPACTED BASE/INSIDE GRADE NO SCALE SLAB AND FOOTING DETAILS DETAIL 1 Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 Standard Grading Guidelines GENERAL The guideline contained herein and the standard details attached hereto represent this firm's standard recommendations for grading and other associated operations on construction projects. These guidelines should be considered a portion of the project specifications. All plates attached hereto shall be considered as part of these guidelines. The Contractor should not vary from these guidelines without prior recommendation by the Geotechnical Consultant and the approval of the Client or his authorized representative. Recommendation by the Geotechnical Consultant and/ or Clients should not be considered to preclude requirements for approval by the controlling agency prior to the execution of any changes. These Standard Grading Guidelines and Standard Details may be modified and/ or superseded by recommendations contained in the text of the preliminary geotechnical report and/or subsequent reports. If disputes arise out of the interpretation of these grading guidelines or standard details, the Geotechnical Consultant shall provide the governing interpretation. DEFINITIONS OF TERMS ALLUVIUM -Unconsolidated soil deposits resulting from flow of water, including sediments deposited in river beds, canyons, flood plains, lakes, fans and estuaries. AS-GRADED (AS-BUILT) -The surface and subsurface conditions at completion of grading. BACKCUT -A temporary construction slope at the rear of earth retaining structures such as buttresses, shear keys, stabilization fills or retaining walls. BACKDRAIN -Generally a pipe and gravel or similar drainage system placed behind earth retaining structures such buttresses, stabilization fills, and retaining walls. BENCH -A relatively level step and near vertical rise excavated into sloping ground on which fill is to be placed. BORROW (Import) -Any fill material hauled to the project site from off-site areas. BUTTRESS FILL -A fill mass, the configuration of which is designed by engineering calculations to retain slope conditions containing adverse geologic features. A buttress is generally specified by minimum key width and depth and by maximum back cut angle. A buttress normally contains a back-drainage system. CIVIL ENGINEER -The Registered Civil Engineer or consulting firm responsible for preparation of the grading plans, surveying and verifying as-graded topographic conditions. CLIENT -The Developer of his authorized representative who is chiefly in charge of the project. He shall have the responsibility of reviewing the findings and recommendations Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 made by the Geotechnical Consultant and shall authorize the Contractor and/or other consultants to perform work and/or provide services. COLLUVIUM -Generally loose deposits usually found near the base of slopes and brought there chiefly by gravity through slow continuous downhill creep ( also see Slope Wash). COMPACTION -Densification of man-placed fill by mechanical means CONTRATOR -A person or company under contract or otherwise retained by the Client to perform demolition, grading and other site improvements. DEBRIS -All products of clearing, grubbing, demolition, contaminated soil materials unsuitable for reuse as compacted fill and/or any other material so designated by the Geotechnical Consultant. ENGINEERING GEOLOGIST -A licensed Engineering Geologist who applies scientific methods, engineering and geologic principles and professional experience to the acquisition, interpretation and use of knowledge of materials of the earth's crust for the evaluation of engineering problems. Geotechnical Engineering encompasses many of the engineering aspects of sil mechanics, rock mechanics, geology, geophysics, hydrology and related sciences. ENGINEERED FILL -A fill of which the Geotechnical Consultant or his representative, during grading, has made sufficient tests to enable him to conclude that the fill has been placed in substantial compliance with the recommendations of the Geotechnical Consultant and the governing agency requirements. EROSION -The wearing away of the ground surface as a result of the movement of wind and/ or water. EXCAVATION -The mechanical removal of earth materials. EXISTING GRADE -The ground surface configuration prior to grading. FILL -Any deposits of soil, rock, soil-rock blends or other similar materials placed by man. FINISH GRADE -The ground surface configuration at which time the surface elevations conform to the approved plan. GEOF ABRIC -Any engineering textile utilized in geotechnical applications including subgrade stabilization and filtering. GEOLOGIST -A representative of the Geotechnical Consultant educated and trained in the field of geology. GEOTECHNICAL CONSULTANT -The Geotechnical Engineering and Engineering Geology consulting firm retained to provide technical services for the project. For the purpose of these specifications, observations by the Geotechnical Consultant include observations by the Soil Engineer, Geotechnical Engineer, Engineering Geologist and those performed by persons employed by and responsible to the Geotechnical Consultant. GEOTECHNICAL ENGINEER -A licensed Geotechnical Engineer or Civil Engineer who applies scientific methods, engineering principles and professional experience to the acquisition, interpretation and use of knowledge of materials of the earth's crust for the Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 evaluation of engineering problems. Geotechnical Engineering encompasses many of the engineering aspects of soil mechanics, rock mechanics, geology, geophysics, hydrology and related sciences. GRADING -Any operation consisting of excavation, filling or combinations thereof and associated operations. LANDSLIDE DEBRIS -Material, generally porous and of low density, produced from instability of natural of man-made slopes. MAXIMUM DENSITY -Standard laboratory test for maximum dry unit weight. Unless otherwise specified, the maximum dry unit weight shall be determined in accordance with ASTM Method of Test D 1557-09. OPTIMUM MOISTURE -Soil moisture content at the test maximum density. RELATIVE COMPACTION -The degree of compaction ( expressed as a percentage) of dry unit weight of a material as compared to the maximum dry unit weight of the material. ROUGH GRADE -The ground surface configuration at which time the surface elevations approximately conform to the approved plan. SITE -The particular parcel of land where grading is being performed. SHEAR KEY -Similar to buttress, however, it is generally constructed by excavating a slot within a natural slope in order to stabilize the upper portion of the slope without grading encroaching into the lower portion of the slope. SLOPE -An inclined ground surface the steepness of which is generally specified as a ratio of horizontal: vertical (e.g.,2:1). SLOPE WASH -Soil and/or rock material that has been transported down a slope by action of gravity assisted by runoff water not confined by channels ( also see Colluvium). SOIL -Naturally occurring deposits of sand, silty, clay, etc., or combinations thereof. SOIL ENGINEER -Licensed Geotechnical Engineer or Civil Engineer experienced in soil mechanics (also see Geotechnical Engineer). STABILIZATION FILL -A fill mass, the configuration of which is typically related to slope height and is specified by the standards of practice for enhancing the stability of locally adverse conditions. A stabilization fill is normally specified by minimum key width and depth and by maximum backcut angle. A stabilization fill may or may not have a back drainage system specified. SUBDRAIN -Generally a pipe and gravel or similar drainage system placed beneath a fill in the alignment of canyons or former drainage channels. SLOUGH -Loose, non-compacted fill material generated during grading operations. TAILINGS -Non-engineered fill which accumulates on or adjacent to equipment haul- roads. TERRACE -Relatively level step constructed in the face of graded slope surface for drainage control and maintenance purposes. TOPSOIL -The presumable fertile upper zone of soil which is usually darker in color and loose. Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 WINDROW -A string of large rocks buried within engineered fill in accordance with guidelines set forth by the Geotechnical Consultant. OBLIGATIONS OF PARTIES The Geotechnical Consultant should provide observation and testing services and should make evaluations in order to advise the Client on geotechnical matters. The Geotechnical Consultant should report his findings and recommendations to the Client or his authorized representative. The client should be chiefly responsible for all aspects of the project. He or his authorized representative has the responsibility of reviewing the findings and recommendations of the Geotechnical Consultant. He shall authorize or cause to have authorized the Contractor and/or other consultants to perform work and/or provide services. During grading the Client or his authorized representative should remain on-site or should remain reasonably accessible to all concerned parties in order to make decisions necessary to maintain the flow of the project. The Contractor should be responsible for the safety of the project and satisfactory completion of all grading and other associated operations on construction projects, including but not limited to, earthwork in accordance with the project plans specifications and controlling agency requirements. During grading, the Contractor or his authorized representative should remain onsite. Overnight and on days off, the Contractor should remain accessible. SITE PREPARATION The Client, prior to any site preparation or grading, should arrange and attend a meeting among the Grading Contractor, the Design Engineer, the Geo technical Consultant, representatives of the appropriate governing authorities as well an any other concerned parties. All parties should be given at least 48 hours notice. Clearing and grubbing should consist of the removal of vegetation such as brush, grass, woods, stumps, trees, roots of trees and otherwise deleterious natural materials from the areas to be graded. Clearing and grubbing should extend to the outside of all proposed excavation and fill areas. Demolition should include removal of buildings, structures, foundations, reservoirs, utilities (including underground pipelines, septic tanks, leach fields, seepage pits, cisterns, mining shafts, tunnels, etc.) and other man-made surface and subsurface improvements from the areas to be graded. Demolition of utilities should include proper capping and/or rerouting pipelines at the governing authorities and the recommendations of the Geotechnical Consultant at the time of demolition. Trees, plants or man-made improvements not planned to be removed or demolished should be protected by the Contractor from damage or injury. Debris generated during clearing, grubbing and/or demolition operations should be wasted from areas to be graded and disposed off-site. Clearing, grubbing and demolition Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 operations should be performed under the observation of the Geo technical Consultant. The Clients or Contractor should obtain the required approvals from the controlling authorities for the project prior, during and/or after demolition, site preparation and removals, etc. The appropriate approvals should be obtained prior to proceeding with grading operations. SITE PROTECTION Protection of the site during the period of grading should be the responsibility of the Contractor. Unless other provisions are made in writing and agreed upon among the concerned parties, completion of a portion of the project should not be considered to preclude that portion or adjacent areas from the requirements for site protection until such time as the entire project is complete as identified by the Geotechnical Consultant, the Client and the regulating agencies. The Contractor should be responsible for the stability of all temporary excavations. Recommendations by the Geotechnical Consultant pertaining to temporary excavations ( e.g., back cuts) are made in consideration of stability of the completed project and, therefore, should not be considered to preclude the responsibilities of the Contractor. Recommendations by the Geotechnical Consultant should not be considered to preclude more restrictive requirements by the regulating agencies. Precautions should be taken during the performance of site clearing, excavations and grading to protect the work site from flooding, ponding, or inundation by poor or improper surface drainage. Temporary provisions should be made during the rainy season to adequately direct surface drainage away from and off the work site. Where low areas cannot be avoided, pumps should be kept on hand to continually remove water during periods of rainfall. During periods of rainfall, plastic sheeting should be kept reasonable accessible to prevent unprotected slopes from becoming saturated. Where necessary during periods of rainfall, the Contractor should install check dams, desilting basins, riprap, sandbags or other devices or methods necessary to control erosion and provide safe conditions. During periods of rainfall, the Geotechnical Consultant should be kept informed by the Contractor as to the nature of remedial or preventative work being performed ( e.g., pumping, placement of sandbags or plastic sheeting, other labor, dozing, etc.). Following periods of rainfall, the Contract or should contract the Geotechnical Consultant and arrange a walk-over of the site in order to visually asses rain related damage. The Geotechnical Consultant may also recommend excavations and testing in order to aid in his assessment. At the request of the Geotechnical Consultant, the Contractor shall make excavations in order to evaluate the extend of rain related damage. Rain related damage should be considered to include, but may not be limited to, erosion, silting, saturation, swelling, structural distress and other adverse conditions identified by the Geotechnical Consultant. Soil adversely affected should be classified to Unsuitable Materials and should be subject to over-excavation and replacement with compacted fill or Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 other remedial grading as recommended by the Geotechnical Consultant. Relatively level areas, where saturated soils and/ or erosion gullies exist to depths of greater than I -foot, should be over-excavated to unaffected, competent material. Where less than I-foot in depth, unsuitable materials may be processed in-place to achieve near optimum moisture conditions, then thoroughly recompacted in accordance with the applicable specifications. If the desired results are not achieved, the affected materials should be over-excavated, then replaced in accordance with the applicable specifications. In slope areas, where saturated soil and/ or erosion gullies exist to depths of greater than I - foot, they should be over-excavated and replaced as compacted fill in accordance with the applicable specifications. Where affected materials exist to depths of I-foot or less below proposed finished grade, remedial grading by moisture conditioning in-place, followed by thorough recompaction in accordance with the applicable grading guidelines herein may be attempted. If the desired results are not achieved, all affected materials should be over- excavated per recommendations herein. As field conditions dictate, other slope repair procedures may be commended by the Geotechnical Consultant. EXCAVATIONS Unsuitable Materials Materials which are unsuitable should be excavated under observation and recommendations of the Geotechnical Consultant. Unsuitable materials include, but may not be limited to, dry, loose, soft, wet, organic compressible natural soils and fractured, weathered, soft bedrock and non-engineered or otherwise deleterious fill materials. Material identified by the Geotechnical Consultant as unsatisfactory due to its moisture conditions should be over-excavated, watered or dried, as needed, and thoroughly blended to a uniform near optimum moisture condition (per Moisture guidelines presented herein) prior to placement as compacted fill. Cut Slopes Unless otherwise recommended by the Geotechnical Consultant and approved by the regulating agencies, permanent cut slopes should not be steeper than 2: 1 (horizontal: vertical). If excavations for cut slopes exposed loose, cohesion less, significantly fractured or otherwise unsuitable material, over-excavation and replacement of the unsuitable materials with a compacted stabilization fill should be accomplished as recommended by the Geotechnical Consultant. Unless otherwise specified by the Geotechnical Consultant, stabilization fill construction should conform to the requirements of the Standard Details. The Geotechnical Consultant should review cut slopes during excavation. The Geotechnical Consultant should be notified by the contractor prior to beginning slope excavations. If, during the course of grading, adverse or potentially adverse geotechnical conditions are encountered which were not anticipated in the preliminary report, the Geotechnical Consultant should explore, analyze and make recommendations to treat these problems. Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 When cut slopes are made in the direction of the prevailing drainage, a non-erodible diversion swale (brow ditch) should be provided at the top-of-cut. Pad Areas All lot pad areas, including side yard terraces, above stabilization fills or buttresses should be over-excavated to provide for a minimum of 3-feet (refer to Standard Details) of compacted fill over the entire pad area. Pad areas with both fill and cut materials exposed and pad areas containing both very shallow (less the 3-feet in thickness (refer to Standard Details). Cut areas exposing significantly varying material types should also be over-excavated to provide for at least a 3-foot thick compacted fill blanket. Geotechnical conditions may require greater depth of over-excavation. The actual depth should be delineated by the Geotechnical Consultant during grading. For pad areas created above cut or natural slopes, positive drainage should be established away from the top-of-slope. This may be accomplished utilizing a berm and/ or an appropriate pad gradient. A gradient in soil area away from the top-of-slope of 2 percent or greater is recommended. Compacted Fill All fill materials should be compacted as specified below or by other methods specifically recommended by the Geotechnical Consultant. Unless otherwise specified, the minimum degree of compaction (relative compaction) should be 90 percent of the laboratory maximum density. Placement Prior to placement of compacted fill, the Contractor should request a review by the Geotechnical Consultant of the exposed ground surface. Unless otherwise recommended, the exposed ground surface should then be scarified (6-inches minimum), watered or dried as needed, thoroughly blended to achieve near optimum moisture conditions, then thoroughly compacted to a minimum of 90 percent of the maximum density. The review by the Geotechnical Consultant should not be considered to preclude requirements of inspection and approval by the governing agency. Compacted fill should be placed in thin horizontal lifts not exceeding 8-inches in loose thickness prior to compaction. Each lift should be watered or dried as needed, thoroughly blended to achieve near optimum moisture conditions then thoroughly compacted by mechanical methods to a minimum of 90percent of laboratory maximum dry density. Each lift should be treated in a like manner until the desired finished grades are achieved. The Contactor should have suitable and sufficient mechanical compaction equipment and watering apparatus on the job site to handle the amount of fill being placed in consideration of moisture retention on the job site to handle the amount of fill being placed in consideration of moisture retention properties of the materials. If necessary, excavation equipment should be "shut down" temporarily in order to permit proper compaction of fills. Earth moving equipment should only be considered a supplement and not substituted for conventional compaction equipment. Mehrdad Dokhanchy File No. l 106F6-21 January 12, 2023 When placing fill in horizontal lifts adjacent to areas sloping steeper than 5: 1 (horizontal: vertical), horizontal keys and vertical benches should be excavated into the adjacent slope area. Keying and benching should be sufficient to provide at least 6-foot wide benches and minimum of 4-feet of vertical bench height within the firm natural ground, firm bedrock or engineered compacted fill. No compacted fill should be placed in an area subsequent to keying and benching unit the area has been reviewed by the Geotechnical Consultant. Material generated by the benching operation should be moved sufficiently away from the bench area to allow for the recommended review of the horizontal bench prior to placement of fill. Typical keying and benching details have been included within the accompanying Standard Details. Within a single fill area where grading procedures dictate two or more separate fills, temporary slopes (false slopes) may be created. When placing fill adjacent to a false slope, benching should be conducted in the same manner as above described. At least a 3-foot vertical bench should be established within the firm core of adjacent approved compacted fill prior to placement of additional fill. Benching should proceed in at least 3-foot vertical increments until the desired finished grades are achieved. Fill should be tested for compliance with the recommended relative compaction and moisture conditions. Field density testing should conform to ASTM Method of Test D 1556-07, and/or D 6938-10. Test should be provided for about every 2 vertical feet or 1,000 cubic yards of fill placed. Actual test intervals may vary as field conditions dictate. Fill found not to be in conformance with the grading recommendations should be removed or otherwise handled as recommended by the Geotechnical Consultant. The Contractor should assist the Geotechnical Consultant and/or his representative by digging test pits for removal determinations and/or for testing compacted fill. As recommended by the Geotechnical Consultant, the Contractor should "shut down" or remove grading equipment from an area being tested. The Geotechnical Consultant should maintain a plan with estimated locations of field tests. Unless the client provides for actual surveying of test locations, the estimated locations by the Geotechnical Consultant should only be considered rough estimates and should not be utilized for the purpose of after-the-fact evaluating of the sequence of fill placement. Moisture For field testing purposes, " near optimum" will vary with material type and other factors including compaction procedures. "Near optimum" may be specifically recommended in Preliminary Investigation Report and/or may be evaluated during grading. Prior to placement of additional compacted fill following an overnight or other grading delay, the exposed surface or previously compacted fill should be processed by scarification, watered or dried as needed, thoroughly blended to near-optimum moisture conditions, then recompacted to a minimum of 90 percent of laboratory maximum dry density. Where wet or other dry or other unsuitable materials exist to depths of greater than 1 foot, the unsuitable materials should be over-excavated. Following a period of flooding, rainfall or overwatering by other means, no additional fill Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 should be placed until damage assessments have been made and remedial grading performed as described herein. Fill Material Excavated on-site materials which are acceptable to the Geotechnical Consultant may be utilized as compacted fill, provided trash, vegetation and other deleterious materials are removed prior to placement. Where import materials are required for use on-site, the Geotechnical Consultant should be notified at least 72 hours in advance of importing, in order to sample and test materials from proposed borrow sites. No import materials should be delivered for use on-site without prior sampling and testing by Geotechnical Consultant. Where oversized rock or similar irreducible material is generated during grading, it is recommended, where practical, to waste such material off-site or on-site in area designated as "nonstructural rock disposal area". Rock placed in disposal areas should be placed with sufficient fines to fill voids. The rock should be compacted in lifts to an unyielding condition. The disposal area should be covered with at least 3 feet of compacted fill which is free of oversized material. The upper 3 feet should be placed in accordance with the guidelines for compacted fill herein. Rocks 8 inches in maximum dimension and smaller may be utilized within the compacted fill, provided they are placed in such a manner that nesting of the rock is avoided. Fill should be placed and thoroughly compacted over and around all rock. The amount of rock should not exceed 40 percent by dry weight passing the ¾ -inch sieve size. The 12-inch and 40 percent recommendations herein may very as field conditions dictate. During the course of grading operations, rocks or similar irreducible materials greater than 8-inches maximum dimension (oversized material) may be generated. These rocks should not be placed within the compacted fill unless placed as recommended by the Geotechnical Consultant. Where rocks or similar irreducible materials of greater than 8 inches but less than 4 feet of maximum dimension are generated during grading, or otherwise desired to be placed within an engineered fill, special handling in accordance with the accompanying Standard Details is recommended. Rocks greater than 4 feet should be broken down or disposed off- site. Rocks up to 4 feet maximum dimension should be placed below the upper 10 feet of any fill and should not be closer than 20-feet to any slope face. These recommendations could vary as locations of improvements dictate. Where practical, oversized material should not be placed below areas where structures or deep utilities are proposed. Oversized material should be placed in windrows on a clean, over-excavated or unyielding compacted fill or firm natural ground surface. Select native or imported granular soil (S.E. 30 or higher) should be placed and thoroughly flooded over and around all windrowed rocks, such that voids are filled. Windrows of oversized material should be staggered so that successive strata of oversized material are not in the same vertical plane. It may be possible to dispose of individual larger rock as field conditions dictate and as recommended by the Geotechnical Consult and at the time of placement. Material that is Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 considered unsuitable by the Geotechnical Consultant should not be utilized in the compacted fill. During grading operations, placing and mixing the materials from the cut and/or borrow areas may result in soil mixtures which possess unique physical properties. Testing may be required of samples obtained directly from the fill areas in order to verify conformance with the specifications. Processing of these additional samples may take two or more working days. The Contractor may elect to move the operation to other areas within the project, or may continue placing compacted fill pending laboratory and field test results. Should he elect the second alternative, fill placed is done so at the Contractor's risk. Any fill placed in areas not previously reviewed and evaluated by the Geotechnical Consultant, and/or in other areas, without prior notification to the Geotechnical Consultant may require removal and recompaction at the Contractor's expense. Determination of over excavations should be made upon review of field conditions by the Geotechnical Consultant. Fill Slopes Unless otherwise recommended by the Geotechnical Consultant and approved by the regulating agencies, permanent fill slopes should not be steeper than 2: 1 (horizontal to vertical). Except as specifically recommended otherwise or as otherwise provided for in these grading guideline (Reference Fill Materials), compacted fill slopes should be overbuilt and cut back to grade, exposing the firm, comp acted fill inner core. The actual amount of overbuilding may vary as field conditions dictate. If the desired results are not achieved, the existing slopes should be over-excavated and reconstructed under the guideline of the Geotechnical Consultant. The degree of overbuilding shall be increased until the desired compacted slope surface condition is achieved. Care should be taken by the Contractor to provide thorough mechanical compaction to the outer edge of the overbuilt slope surface. Although no construction procedure produces a slope free from risk of future movement, overfilling and cutting back of slope to a compacted inner core is, given no other constraints, the most desirable procedure. Other constraints, however, must often be considered. These constraints may include property line situations ,access, the critical nature of the development and cost. Where such constrains are identified, slope face compaction may be attempted by conventional construction procedures including back rolling techniques upon specific recommendation by the Geotechnical Consultant. As a second-best alternative for slopes of 2: 1 (horizontal to vertical) or flatter, slope construction may be attempted as outlined herein. Fill placement should proceed in thin lifts, (i.e., 6 to 8-inch loose thickness). Each lift should be moisture conditioned and thoroughly compacted. The desired moisture condition should be maintained and/ or reestablished, where necessary, during the period between successive lifts. Selected lifts should be tested to ascertain that desired compaction is being achieved. Care should be taken to extend compactive effort to the outer edge of the slope. Each lift should extend horizontally to the desired finished slope surface or more as needed to ultimately establish Mehrdad Dokhanchy File No. 1106F6-21 January 12, 2023 desired grades. Grade during construction should not be allowed to roll off at the edge of the slope. It may be helpful to elevate slightly the outer edge of the slope. Slough resulting from the placement of the individual lifts should not be allowed to drift down over previous lifts. At intervals not exceeding 4 feet in vertical slope height or the capability of available equipment, whichever is less, fill slopes should be thoroughly back rolled utilizing a conventional sheeps foot-type roller. Care should be taken to maintain the desired moisture conditions and/or reestablishing same as needed prior to back rolling. Upon achieving final grade, the slopes should gain be moisture conditioned and thoroughly back rolled. The use of a side-boom roller will probably be necessary and vibratory methods are strongly recommended. Without delay, so as to avoid (if possible) further moisture conditioning, the slopes should then be grid-rolled to achieve a relatively smooth surface and uniformly compact condition. In order to monitor slope construction procedure, moisture and density tests will be taken at regular intervals. Failure to achieve the desired results will likely result in a recommendation by the Geotechnical Consultant to over-excavate the slope surfaces followed by reconstruction of the slopes utilizing overfilling and cutting back procedures and/or further attempt at the conventional back rolling approach. Other recommendations may also be provided which would be commensurate with field conditions. Where placement of fill above a natural slope or above a cut slope in proposed, the fill slope configuration as presented in the accompanying Standard Details should be adopted. For pad areas above fill slope, positive drainage should be established away from the top- of-slope. This may be accomplished utilizing a berm and pad gradients of at least 2 percent in sol areas. Off-Site Fill Off-site fill should be treated in the same manner as recommended in these specifications for site preparation, excavation, drains, compaction, etc. Off-site canyon fill should be placed in preparation for future additional fill, as shown in the companying Standard Details. Off-site fill subdrains temporarily terminated (up canyon) should be surveyed for future relocation and connection. STAKING In all fill areas, the fill should be compacted prior to the placement of the stakes. This particularly is important on fill slopes. Slopes stakes should not be placed until the slope is thoroughly compacted (back rolled). If stakes must be placed prior to the completion of compaction procedures, it must be recognized that they will be removed and/or demolished at such time as compaction procedures resume. In order to allow for remedial grading operations, which could include over-excavations or slope stabilization, appropriate staking off sets should be provided. For finished slope and stabilization backcut areas, we recommend at least a 10-feet setback from proposed toes and tops-of-cut. Mehrdad Dokhanchy File No. l 106F6-21 January 12, 2023 DRAINAGE Canyon subdrain systems specified by the Geotechnical Consultant should be installed in accordance with the Standard Details. Typical subdrains for compacted fill buttresses, slope stabilization or side hill masses, should be installed in accordance with the specifications of the accompanying Standard Details. Roof, pad and slope drainage should be directed away from slopes and areas of structures to suitable disposal areas via non-erodible devices (i.e., gutters, downspout, concrete swales). For drainage over soil areas immediately away from structures (i.e., within 4 feet), a minimum of 4 percent gradient should be maintained. Pad drainage of at lease 2 percent should be maintained over soil areas. Pad drainage may be reduced to at least 1 percent for projects where no slopes exist, either natural or man-made, or greater than 10-feet in height and where no slopes are planned, either natural or man-made, steeper than 2:1 (horizontal to vertical slope ratio). Drainage patterns established at the time of fine grading should be maintained throughout the life of the project. Property owners should be made aware that altering drainage patterns can be detrimental to slope stability and foundation performance. SLOPE MAINTENANCE Landscape Plants In order to enhance Surficial slope stability, slope planting should be accomplished at the completion of grading. Slope planting should consist of deep-rooting vegetation requiring little watering. Plants native to the Southern California area and plants relative to native plants are generally desirable. Plants native to other semi-arid and arid areas may also be appropriate. A Landscaping Architect would be the bast party to consult regarding actual types of plants and planting configuration. Irrigation Irrigation pipes should be anchored to slope faces, not placed in trenches excavated into slope faces. Slope irrigation should be minimized. If automatic timing devices are utilized or irrigation systems, provisions should be made for interrupting normal irrigation during periods of rainfall. Though not a requirement, consideration should be given to the installation of near-surface moisture monitoring control devices. Such devices can aid in the maintenance of relatively uniform and reasonably constant moisture conditions. Property owners should be made aware that overwatering of slopes is detrimental to slope stability. Maintenance Periodic inspections of landscaped slope areas should be planned and appropriate measures should be taken to control weeds and enhance growth of the landscaping plants. Some areas may require occasional replanting and/or reseeding. Mehrdad Dokhanchy File No. l 106F6-21 January 12, 2023 Terrace drains and down drains should be periodically inspected and maintained free of debris. Damage to drainage improvements should be repaired immediately. Property owners should be made aware that burrowing animals can be detrimental to slope stability. A preventative program should be established to control burrowing animals. As a precautionary measure, plastic sheeting should be readily available, or kept on hand, to protect all slope areas from saturation by periods of heavy or prolonged rainfall. This measure is strongly recommended, beginning with the period of time prior to landscape planting. Repairs If slope failures occur, the Geotechnical Consultant should be contracted for a field review of site conditions and development or recommendations for evaluation and repair. If slope failures occur as a result of exposure to periods of heavy rainfall, the failure area and currently unaffected area should be covered with plastic sheeting to protect against additional saturation. In the accompanying Standard Details, appropriate repair procedures are illustrated for superficial slope failures (I.e., occurring typically within the outer 1 foot to 3 feet of a slope face). TRENCH BACKFILL Utility trench backfill should, unless otherwise recommended, be compacted by mechanical means. Unless otherwise recommended, the degree of compaction should be a minimum of 90 percent of the laboratory maximum density. Backfill of exterior and interior tranches extending below a 1: 1 projection from the outer edge of foundations should be mechanically compacted to a minimum of 90 percent of the laboratory maximum density. In cases where clean granular materials are proposed for use in lieu of native materials or where flooding or jetting is proposed, the procedures should be considered subject to review by the Geotechnical Consultant. Clean Granular backfill and/ or bedding are not recommended in slope areas unless provisions are made for a drainage system to mitigate the potential build-up of seepage forces. STATUS OF GRADING Prior of proceeding with any grading operation, the Geotechnical Consultant should be notified at least two working days in advance in order to schedule the necessary observation and testing services. Prior to any significant expansion or cut back in the grading operation, the Geotechnical Consultant should be provided with adequate notice (i.e., two days) in order to make appropriate adjustments in observation and testing services. Following completion of grading operations and/or between phase of a grading operation, the Geotechnical Consultant should be provided with at least two working days notice in advance of commencement of additional grading operations. ------------------------------- January 16, 2022 Nichole Fine City of Carlsbad Land Development Engineering 1635 Faraday Avenue Carlsbad, California 92008 SUBJECT: File No. 1106F6-21 SITE INSPECTION Dear Ms. Fine: Response to Third Party Review Proposed Residential Building Site 1098 Magnolia A venue City of Carlsbad P.O. Box 1195 Lakeside, California 92040 (619) 443-0060 In response to the third part review by Unknow Entity, Project No. MS2022-0003, Grading Permit No. GR2021-0047,Subject 1098 Magnolia Avenue (2nd review) dated October 29, 2022. 1. The report was prepared in accordance with the 2019 California Building Code and ASCE 7-16. 2. Please refer to the current civil plan. 3. The sampling obtained during the investigation was a grab sample from the excavation pile. 4. Test results were provided per ASTM methods as outlined on page 10. 5. Please see the attached Plate I. 6. The Site Class should be default D. Please see amended report. 7. Please see amended report. 8. Please see amended report. 9. During our initial investigation, we were unaware that the project was part of a Tentative Parcel Map. A corrosive sample will be obtained, and information provided. 1098 Magnolia Ave File No. 1106F6-21 January 16, 2023 10. The values for total settlement of 1 inch and for differential settlement of½ inch should be used. 11. The proposed foundation system will meet and satisfy Section 1808.6 of the 2019 CBC for expansive soils. The onsite soils are considered to have a low expansion index of 21. 12. Please see the Standard Grading Guidelines that are part of our report. 13. The depth of the Old Paralic Deposits will be determined with an additional trench on January 31, 2023. However, Soil Testers did the six houses immediately to the north and the competent native soils were encountered in depths varying from 2 feet up to 6 feet. 14. The recommendations for possible temporary backcuts and slopes should meet OSHA requirements for Soil Type C. 15. Utility trenches in proximity to the proposed structure should adhere to the 2019 CBC Code of 1 : 1 slope. 16. The recommendations for the proposed driveway have been added to the amended report. 17. The potential for storm water infiltration at the subject site is good. Reviewing the National Resources Conservation Service (NRCS), identifies the hydrologic soil group as B. This grouping considers infiltration to be between 0.57 to 1.98 in/hr. based upon soil profile and zones. The area is considered to be loamy coarse sand, loamy sand, to sand. The loamy sand classification will have silt or clay mixture with the sand that will vary percentages causing the infiltration to vary too. The rating for runoff is Medium. Within our limited soils investigation, we had found the soil to be consistence down to four feet. Our knowledge of the area the loamy sand to sand goes between two and six feet depth with the clay to be very low, below 18. With our site, we had encountered our clay to be 21 with the range for sandy loamy soils to range between 12 to 20 based upon the farmland condition for growing. This mixture is to retain water within the soil if there are more sandy conditions below. The vegetation is part of the cycle for stormwater retention and runoff. The grading plan doesn't have the full site being graded only the house pad and driveway with hardscape, walkways. This method of development meets with the stormwater BMP for limited grading for non-disturbance, by minimizing runoff. In our professional opinion this site will not cause harm to the neighbors and the community during the construction phase. 2 1098 Magnolia Ave File No. 1106F6-21 January 16, 2023 18. Please see the Standard Grading Guidelines that are part of our report. If we can be of any further assistance, please do not hesitate to contact our office. This opportunity to be of service is sincerely appreciated. Site Inspection dated January 12, 2023 (Amended from July 19, 2022), is attached to this response. Respectfully submitted, CCC/mlj 3 March 8, 2023 Nichole Fine City of Carlsbad Land Development Engineering 1635 Faraday Avenue Carlsbad, California 92008 SUBJECT: Dear Ms. Fine: File No. 1106F6-21 SITE INSPECTION Response to Third Party Review Proposed Residential Building Site 1098 Magnolia A venue City of Carlsbad P.O. Box 1195 Lakeside, California 92040 (619) 443-0060 In response to the third part review by Unknow Entity, Project No. MS2022-0003, Grading Permit No. GR2021-0047,Subject 1098 Magnolia Avenue (3rd review) dated February 10, 2023. 1. The following site specific information and laboratory testing included below should be used for this project. 2. The depths of removals for the remedial grading for the proposed hardscape and improvements should at minimum extend to the formational soils at 2 to 2.5 feet in depth. The removals do not need to extend beyond the proposed hardscape such as driveways and sidewalks. However, the final determination should be done by the grading contractor and the soil technician in the field. 3. During the additional trenching on January 31, 2023, my Engineering Geologist, Bryan Miller-Hicks determined the Old Paralic Deposits were between 2 and 2.5 feet in depth. 1098 Magnolia Ave File No. 1106F6-21 March 8, 2023 CHEMICAL TESTING: The test is to determine the pH, minimum resistivity, soluble chlorides, and soluble sulfate content of the foundation soil were performed for us by Clarkson Laboratory and Supply Inc. The test indicates that the soil has a pH range of 7.2, per the California Test Method No. 643. C.Opharclt,o.2003 pH Scale 10-1 10-S 10-6 10-9 10-12 2 3 4 5 6 7 8 9 10 11 12 13 14 , o-13 1 o-11 Acidic Neutral Increasing hydroge n ... 10-S Basic , o-2 Increasing hydroxide Ions ► pH scale, by Virtual Chembook, Elmhurst College, by Charles E. Ophardt, 2003, http:// chemistry, Elmhurst.edu/vchembook/images2/184phscale.gif. From the California Test Method No. 643, indicates the factor that contributes to corrosion includes the presence of soluble salts, soil and water resistivity, and soil and water pH, along with the presence of oxygen. The following chart will show the soil and the added water amounts indicating the degree of acidity or alkalinity. WATERADDEDin (mL) RESISTIVITY (ohm-cm) Base 10 ml 13,000 5-15 ml 5,700 5-20 ml 4,100 5-25 ml 3,000 5-30 ml 2,800 5-35 ml 2,700 5-40 ml 2,800 5-45 ml 2,900 2 1098 Magnolia Ave File No. 1106F6-21 March 8, 2023 See below table 1, for the classification pertaining to the resistivity of the soil tested. TABLE 1: SOIL R.ESISTIVIT'f CLASSIFICATION1 in ohm.cm The recommendation provided from Clarkson Laboratory and Supply Inc, pertaining to the resistivity of the soil coming into contact with concrete and ferrous metals pipes as follows: 35 years to perforation for a 16 gauge metal culvert. 45 years to perforation for a 14 gauge metal culvert. 63 years to perforation for a 12 gauge metal culvert. 80 years to perforation for a 10 gauge metal culvert. 98 years to perforation for an 8 gauge metal culvert. If the design is going to use direct contact of ferrous metals in the soil, then we recommend the project and materials specified and used should be determined by the Civil Engineer with an understanding of cathodic protection for the recommendations. Sulfate and Chloride Content A sample of the onsite soil from 2 feet below the surface was tested to assist in an evaluation of the degree of sulfates attack on ordinary (type II) concrete. The test was performed in general accordance with California Test Method No. 417, and yielded a soluble sulfate content of 78 ppm. or 0.008%, with the range ofup to 150 ppm. The test result indicates a "negligible" degree of sulfate attack. The type of concrete specified and used should be determined by the Structural Engineer. The Soluble Chloride Method of testing soils containing Chloride used the California test Method No. 422, and yielded a soluble Chloride content of 32 ppm. or 0.003%. 3 1098 Magnolia Ave File No. 1106F6-21 March 8, 2023 Carbonate and Sulfide Content The Carbonate Method of testing soils containing Calcium carbonate used the ASTM Test Method No. D4373. This test is being done due to the location of the site having sandy soils looking for cementing agents, are water soluble at pH <7.5, and are soft on the Mohs' scale compared to other soil minerals. The sample yielded absent for Carbonate. A Saturated Paste Extract Sulfide (S2) test was made following the ASTM Test Method No. D4658, is a water-soluble test that helps identify the nutrients are soluble in the soil solution, including high sodium or salt and calcium levels. This test is being done due to the location of the site having alluvial soils which yielded a soluble content of <0.1 ppm. Moisture Content and Resistivity "Moisture content is a more important factor in soil corrosivity than any other variable. As water is one of the three components necessary for electrochemical corrosion ( the other two being oxygen and metal), corrosion will not occur if the soil is completely dry. Experimental evidence dictates that increased moisture content decreases resistivity of soils, in tum increasing their corrosive potential. Note that when the saturation point of soil is reached, additional moisture has little or no effect on resistivity." The relationship between the resistiYity of the soil, a particular soil class, and the corrosion resistance for gah·anized steel is summarized in the following table. Soil Class Corrosion Resistance in Electrical Resistivity, \°\ -cm Gah-anized Steel Sandy Excellent 6,000 -10,000 Loams Good ,500 -6,000 Clay Fair 2,000 -4,500 Peat/muck Bad 0 -2,000 Conversely, the relationsrup between soil resistivity and corrosion potential in uncoated steel is shown in the table below. Resistance Classification io Soil Resistivity, C orrosion Potential U1rnoated Steel W-cm Low 0 -2000 Severe M edium 2000 -10000 Moderate High 10000 -30000 Mild Very High >30000 one 4 1098 Magnolia Ave File No. 1106F6-21 March 8, 2023 Corrosive Soils, Cause, Effects and Mitigation, by Hossein Arbabi, Testing Engineers, Inc., White paper, www.Testing-engineers.com/casel .html. CORROSION TESTING Soil Testers does not practice in the field of corrosion engineering. If after grading the soils seems susceptible to corrosion than Soil Testers can collect a sample to be tested and evaluate the corrosion potential to any subsurface metal structures and be included in the compaction report. Any further evaluation should be done by a corrosion engineer to provide recommendations. If we can be of any further assistance, please do not hesitate to contact our office. This opportunity to be of service is sincerely appreciated. Respectfully submitted, CCC/mlj 5