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HomeMy WebLinkAboutSDP 02-16; COASTLINE COMMUNITY CHURCH; UPDATE GEOTECHNICAL REPORT; 2018-10-12UPDATE GEOTECHNICAL REPORT COASTLINE COMMUNITY .CHURCH EXPANSION 2215 CALLE BARCELONA CARLSBAD, CALIFORNIA -i'v r1r1s FEB 2 0 219 LAND DE\iLL(".E T ENGNELkI J PREPARED FOR COASTLINE COMMUNITY CHURCH % GRANT GENERAL CONTRACTORS CARLSBAD, CALIFORNIA OCTOBER 12, 2018 PROJECT NO. G1968-11-02 $L GEOCON INCORPORATED GE 01 E C H N IC Al • ENVIRONMENTAL U MATE RI A IS Project No. G1968-11-02 October 12, 2018 Coastline Community Church % Grant General Contractors 5051 Avenida Encinas Carlsbad, California 92008 Attention: Mr. Jim Grant Subject: UPDATE GEOTECHNICAL REPORT COASTLINE COMMUNITY CHURCH EXPANSION 2215 CALLE BARCELONA CARLSBAD, CALIFORNIA Dear Mr. Grant: In accordance with your authorization of our proposal (LG-18211) dated June 5, 2018, we prepared this update geotechnical report for use in design and construction of the proposed expansion to the existing Coastline Community Church facility located at 2215 Calle Barcelona in Carlsbad, California. The accompanying report presents the results of our study and conclusions and recommendations pertaining to the geotechnical aspects of the proposed expansion. Provided the recommendations contained in this update report are followed, the site is considered suitable for construction and support of the proposed project. Should you have questions regarding this report, or if we may be of further service, please contact the undersigned at your convenience. Very truly yours, GEOCON iNCORPORATED ; ?Hoobs CEG 1524 JH: SFW:dmc (e-mail) Addressee JOHN 1 HOOSS No. 1524 CL CERTIFIED * ENGINEERING * GEOLOGIST \4 N.9P CAt-Z Shawn Foy Weedon GE 2714 ( oESS10 crws$ a No. 2714 6960 Flanders Drive I San Diego, California 92121-2974 0 Telephone 858.558.6900 U Fax 858.558.6159 TABLE OF CONTENTS PURPOSE AND SCOPE . 1 PREVIOUS GRADING AND PROPOSED DEVELOPMENT .......................................................... 1 SOIL AND GEOLOGIC CONDITIONS .............................................................................................2 3.1 Alluvium (Qal) ...........................................................................................................................3 3.2 Delmar Formation (Td)...............................................................................................................3 3.3 Torrey Sandstone (Tt).................................................................................................................3 GROUNDWATER ...............................................................................................................................3 GEOLOGIC HAZARDS ......................................................................................................................4 5.1 Faulting and Seismicity ..............................................................................................................4 5.2 Ground Rupture..........................................................................................................................5 5.3 Liquefaction ................................................................................................................................ S 5.4 Seiches and Tsunamis.................................................................................................................6 5.5 Buttress Fill.................................................................................................................................6 CONCLUSIONS AND RECOMMENDATIONS................................................................................7 6.1 General........................................................................................................................................7 6.2 Excavation and Soil Characteristics ...........................................................................................7 6.3 Seismic Design Criteria...............................................................................................................8 6.4 Temporary Excavations............................................................................................................10 6.5 Grading.....................................................................................................................................10 6.6 Shallow Foundations and Concrete Slabs-On-Grade Recommendations.................................11 6.7 Concrete Flatwork ....................................................................................................................15 6.8 Retaining Walls ........................................................................................................................16 6.9 Lateral Loading.........................................................................................................................18 6.10 Preliminary AC and PCC Pavement Recommendations..........................................................18 6.11 Interlocking Pervious Concrete Paver Recommendations........................................................21 6.12 Site Drainage and Moisture Protection.....................................................................................23 6.13 Foundation Plan Review...........................................................................................................24 LIMITATIONS AND UNIFORMITY OF CONDITIONS MAPS AND ILLUSTRATIONS Figure 1, Vicinity Map Figure 2, Geologic Map (Map Pocket) Figure 3, Wall/Column Footing Dimension Detail Figure 4, Retaining Wall Loading Diagram Figure 5, Typical Retaining Wall Drain Detail LIST OF REFERENCES UPDATE GEOTECHNICAL REPORT 1. PURPOSE AND SCOPE This report presents the results of our update geotechnical study for the proposed expansion project to the existing Coastline Community Church facility located at 2215 Calle Barcelona in Carlsbad, California (see Vicinity Map, Figure 1). The purpose of this geotechnical report is to evaluate the surface and subsurface soil conditions and general site geology, and to identify geotechnical constraints that may affect the proposed expansion project including faulting, liquefaction and seismic shaking based on the 2016 CBC seismic design criteria. In addition, this report provides recommendations for remedial grading, building foundation and slab-on-grade, retaining wall, new pavement and concrete flatwork for use in design and construction of the expansion project. The scope of this study included a site visit and a review of: Grading, Streets and Utilities Plan for Coastline Community Church, 2215 Calle Barcelona, Carlsbad, California, prepared by Fuscoe Engineering, Submittal #3 dated October 12, 2018. Final Report of Testing and Observation Services During Site Grading, Arroyo La Costa Church Site, Carlsbad, California, prepared by Geocon Incorporated, dated April 13, 1999 (project No. 05871-12-01). Final Report of Testing and Observation Services Performed During Site Grading, Coastline Community Church, Carlsbad, California, prepared by Geocon Incorporated, dated December 20, 2006 (Project No. 05871-52-24A). 2. PREVIOUS GRADING AND PROPOSED DEVELOPMENT The site consists of developed land that was graded in 1997 and 2006 creating a graded church site with an existing building finish pad grade of roughly 104 feet above Mean Sea Level (MSL), storage shed, play areas, parking lots and driveways. The Geologic Map, Figure 2, shows the current geologic conditions, existing buildings/improvements and proposed buildings and improvements. The referenced Fuscoe grading plan was used as the base map for our figure. Sheet grading on the property occurred in 1997 during grading operations for the designated Arroyo La Costa church site pad. The previous grading consisted of the partial removal of surficial soil extending roughly to the groundwater table on the northeastern portion of the site, complete removal of surficial soil on the remainder of the site, and the construction of a buttress fill on the southern portion of the site to stabilize weak formational materials. Alluvium left in place below the groundwater table has an estimated thickness of approximately 10 to 15 feet. Grading consisted of the placement of compacted fill to achieve sheet-grade elevations. A surcharge fill was placed and settlement monitoring of the fill and buried alluvium was performed until surveyor readings Project No. G1968-11-02 - 1 - October 12, 2018 essentially showed negligible vertical movements. The 1997 fill was placed under the observation and compaction testing services of Geocon Incorporated for the overall Arroyo La Costa development as discussed on our referenced report dated April 13, 1999. We performed testing and observation services during the fine grading of the existing church facility and parking lots to achieve its current finish grade elevations as discussed in our referenced report dated December 20, 2006. Additional fill up to roughly 18 feet thick was placed on the sheet-graded pad. The construction also included retaining walls, play areas, tot lot, driveways and terraced parking lots. The existing buildings and improvements were constructed in 2007 or thereafter with the church community building supported by a post-tensioned foundation system. The majority of the existing Worship Center Building consists of compacted fill overlying alluvium left in place with the southwest corner consisting of compacted fill overlying the Delmar Formation. The existing Café Building consists of compacted fill overlying alluvium left in place and the Delmar Formation. The proposed expansion project will include the following. An expansion and tenant improvements of the existing Worship Center and Café Buildings on the northeast portion of the property. A new one-story Ministry Building on the northwest portion of the property with a finish floor elevation of 100.0 feet MSL. A new, two-story Maintenance Building on the southeast corner of the site south of Drive A with a finish floor elevation of 132.5 feet MSL. . A new Drive C located between existing Drives A and B. This will include adding 68 parking stalls. Three biofiltration basins and various courtyard and surface improvements. Concrete payers on the west terminus of Drive A. Construction of several retaining walls with a maximum height of about 8 feet to achieve proposed finish grades. 3. SOIL AND GEOLOGIC CONDITIONS Based on review of the referenced geotechnical reports, the church facility is underlain by previously placed compacted fill overlying the Delmar Formation and alluvium left in place below the groundwater table. The existing fill thickness is roughly 20 to 25 feet across the site. Laboratory tests perfcrmed on samples of the on-site fill during previous grading operations indicate the near surface soil has a "very low" expansion potential (expansion index of 20 or less) and an "SO" sulfate severity exposure. Project No. G1968-11-02 -2- October 12, 2018 3.1 Alluvium (Qal) During previous remedial grading operations, the majority of alluvium present at the site was removed and replaced with compacted fill. However, due to the presence of shallow groundwater, a portion of the alluvium in the northeastern portion of the site was left in place. Compacted fill was placed over the alluvium in this area to reach current site elevation. The alluvium generally consists of dark brown, sandy clays to clayey sands. The maximum thickness of alluvium is estimated to be approximately 15 feet near the northeast corner of the property. The alluvium left in place is suitable to support the proposed expansion project. 3.2 Delmar Formation (Td) The Eocene-aged Delmar Formation, consisting of hard, greenish-gray to brown, claystones and siltstones with layers of silty, fine to coarse sandstones, underlies the compacted fill soils throughout the majority of the site. Due to the cover of compacted fill at the site, it is not anticipated that this formational unit will be encountered during grading operations. The Delmar Formation is suitable to support the proposed expansion project. 3.3 Torrey Sandstone (Tt) The Tertiary-aged Torrey Sandstone consists of dense, damp to moist, light tan to orange-brown, silty, fine sandstone with varying amounts of clay. The Torrey Sandstone was generally deposited conformably upon the Delmar Formation and appears to dip from horizontal to ten degrees to the southwest. The contact is approximately located at an elevation of 130 MSL near the southern property line. The formational Torrey Sandstone is not anticipated to be encountered during grading operations. 4. GROUNDWATER We observed groundwater at the base of the surficial soil removals performed in 1999 during the previous grading operations. We expect that the static groundwater table would be in excess of 15 to 20 feet below existing grades for the existing and new buildings. We do not expect groundwater to affect the expansion project; however, it is not uncommon for shallow seepage conditions to develop where none previously existed. Seepage is dependent on seasonal precipitation, irrigation; land use, among other factors, and vary as a result. Proper surface drainage will be important to future performance of the building. Project No. G1968-11-02 -3- October 12, 2018 5. GEOLOGIC HAZARDS 5.1 Faulting and Seismicity A review of geologic literature and our knowledge of the general area indicate that the site is not underlain by active, potentially active or inactive faults. An active fault is defined by the California Geological Survey (CGS) as a fault showing evidence for activity within the last 11,000 years. The site is not located within a State of California Earthquake Fault Zone. According to the computer program EZ-FRISK (Version 7.65), nine known active faults are located within a search radius of 50 miles from the property. We used the 2008 USGS fault database that provides several models and combinations of fault data to evaluate the fault information. Based on this database, the nearest known active fault is the Newport-Inglewood/Rose Canyon Fault system, located approximately 5 miles west of the site and is the dominant source of potential ground motion. Earthquakes that might occur on the Newport-Inglewood/Rose Canyon Faults or other faults within the southern California and northern Baja California area are potential generators of significant ground motion at the site. The estimated deterministic maximum earthquake magnitude and peak ground acceleration for the Newport-Inglewood/Rose Canyon Faults are 7.5 and 0.38g, respectively. Table 5.1.1 lists the estimated maximum earthquake magnitude and peak ground acceleration for the most dominant faults in relationship to the site location. We calculated peak ground acceleration (PGA) using Boore-Atkinson (2008) NGA USGS2008, Campbell-Bozorgniá (2008) NGA USGS2008, and Chiou-Youngs (2007) NGA USGS2008 acceleration-attenuation relationships. TABLE 5.1.1 DETERMINISTIC SPECTRA SITE PARAMETERS Fault Name Distance from Site (miles) Maximum Earthquake Magnitude (Mw) Peak Ground Acceleration Boore- Atkinson 2008 (g) Campbell- Bozorgnia 2008 (g) Chiou- Youngs 2007 (g) Newport-Inglewood 5 7.5 0.33 0.30 0.38 Rose Canyon 5 6.9 0.29 0.28 0.32 Coronado Bank 21 7.4 0.19 0.13 0.15 Palos Verdes Connected 21 7.7 0.20 0.14 0.18 Elsinore 23 7.9 0.20 0.13 0.18 Earthquake Valley 40 6.8 0.09 0.06 0.05 Palos Verdes 41 7.3 0.11 0.08 0.08 San Joaquin Hills 43 7.1 0.10 0.09 0.08 San Jacinto 49 7.9 0.12 0.08 0.10 Project No. G1968-ll-02 -4- October 12, 2018 We used the computer program EZ-FRISK to perform a probabilistic seismic hazard analysis. The computer program EZ-FRISK operates under the assumption that the occurrence rate of earthquakes on each mapped Quaternary fault is proportional to the faults slip rate. The program accounts for earthquake magnitude as a function of fault rupture length, and site acceleration estimates are made using the earthquake magnitude and distance from the site to the rupture zone. The program also accounts for uncertainty in each of following: (1) earthquake magnitude, (2) rupture length for a given magnitude, (3) location of the rupture zone, (4) maximum possible magnitude of a given earthquake, and (5) acceleration at the site from a given earthquake along each fault. By calculating the expected accelerations from considered earthquake sources, the program calculates the total average annual expected number of occurrences of site acceleration greater than a specified value. We utilized acceleration-attenuation relationships suggested by Boore-Atkinson (2008) NGA USGS2008, Campbell-Bozorgnia (2008) NGA USGS2008, and Chiou-Youngs (2007) NGA USGS2008 in the analysis. Table 5.1.2 presents the site-specific probabilistic seismic hazard parameters including acceleration-attenuation relationships and the probability of exceedence. TABLE 5.1.2 PROBABILISTIC SEISMIC HAZARD PARAMETERS Probability of Exceedence Peak Ground Acceleration Boore-Atkinson, 2008 (g) Campbell-Bozorgnia, 2008 (g) Chiou-Youngs, 2007 (g) 2% in a 50 Year Period 0.51 0.43 0.50 5% in a 50 Year Period 0.38 0.32 0.36 1O%ina5O Year Period 0.30 0.24 0.27 While listing peak accelerations is useful for comparison of potential effects of fault activity in a region, other considerations are important in seismic design, including the frequency and duration of motion and the soil conditions underlying the site. Seismic design of the structures should be evaluated in accordance with the California Building Code (CBC) guidelines currently adopted by the City of Carlsbad. 5.2 Ground Rupture Ground surface rupture occurs when movement along a fault is sufficient to cause a gap or rupture where the upper edge of the fault zone intersects the earth surface. The potential for ground rupture is considered to be negligible due to the absence of active faults at the subject site. 5.3 Liquefaction Liquefaction typically occurs when a site is located in a zone with seismic activity, onsite soil is cohesionless/silt or clay with low plasticity, groundwater is encountered within 50 feet of the surface, Project No. G1968-11-02 -5- October 12, 2018 and soil relative densities are less than about 70 percent. If the four previous criteria are met, a seismic event could result in a rapid pore-water pressure increase from the earthquake-generated ground accelerations. Based on our review of previous reports and review of published geologic literature, it is our opinion that the potential for liquefaction is very low considering the dense nature of the underlying compacted fill, densified alluvial soil from the placement of fill and previous surcharge, and very dense formational materials. 5.4 Seiches and Tsunamis Seiches are caused by the movement of an inland body of water due to the movement from seismic forces. The potential of seiches to occur is considered to be very low due to the absence of a nearby inland body of water. A tsunami is a series of long-period waves generated in the ocean by a sudden displacement of large volumes of water. Causes of tsunamis include underwater earthquakes, volcanic eruptions, or offshore slope failures. The site is located approximately 3 miles from the Pacific Ocean at an elevation of at least 90 feet above Mean Sea Level. Therefore, the risk of tsunamis affecting the site is negligible. 5.5 Buttress Fill A drained buttress fill was constructed to mitigate potential gross and surficial slope instability at the site. The buttress fill was constructed where a landslide and bedding plane shears were previously identified. The landslide was completely removed, and a keyway was excavated. A heel drain was installed during construction of the buttress fill on the site. The heel drain was "as-built" for location and elevation by the project civil engineer. The heel drain generally consisted of a 6-inch-diameter PVC perforated pipe placed in crushed aggregate surrounded by Mirafi 140N filter fabric. The drain was generally placed at the heel of the buttress fill keyway and constructed at a gradient of at least 1 percent. In addition, drainage panels (Miradrain 5000) were placed at 30 feet on center along the face of the stabilization fill backcut and were connected to the heel drain. The heel drain was extended to the desilting basin in the northwest corner of the site and discharges at surface grade. A concrete wall was constructed at the outlet point to protect against blockage or destruction of the heel drain outlet. The heel drain outlet should be maintained regularly to prevent sediment and debris from obstructing the free flow of water out of the heel drain system. The heel drain location is shown on the Geologic Map (Figure 2). The results of our prior analyses for gross stability indicate that the existing buttress fill has a calculated factor of safety in excess of 1.5. Project No. G1968-11-02 -6- October 12, 2018 6. CONCLUSIONS AND RECOMMENDATIONS 6.1 General 6.1.1 From a geotechnical engineering standpoint, it is our opinion that the proposed expansion project to the existing Coastline Community Church facility is suitable provided the recommendations presented herein are implemented in design and construction of the project. 6.1.2 With the exception of possible moderate to strong seismic shaking, we did not observe or know of significant geologic hazards to exist on the site that would adversely affect the proposed project. 6.1.3 The referenced previous geotechnical reports indicate the site is underlain by compacted fill, alluvium and the Delmar Formation. Fill depths of roughly 20 to 25 exist beneath the site based on information presented in the referenced geotechnical reports. Based on our observations from a limited site reconnaissance, it appears the existing fill has provided suitable bearing support for the existing buildings and improvements, and we expect it should be suitable for the expansion project including new foundations and slab-on-grade. 6.1.4 We expect that the planned structures will be supported by a foundation system founded into properly compacted fill with conventional shallow foundation systems or a post- tensioned foundation system. 6.1.5 We do not expect groundwater or seepage to be encountered during construction of the proposed improvements. However, development during the rainy season can cause wet soil conditions and localized seepage near ponded water. 6.1.6 Excavation of the existing fill should generally be possible with moderate effort using conventional, heavy-duty grading and trenching equipment. 6.2 Excavation and Soil Characteristics 6.2.1 Excavation of the in-situ soil should be possible with moderate to heavy effort using conventional heavy-duty equipment. Excavation of the formational materials will require very heavy effort and may generate oversized material using conventional heavy-duty equipment during the grading operations. Oversized rock (rocks greater than 12-inches in dimension) may be generated with the formational materials that can be incorporated into landscape use or deep compacted fill areas, if encountered. Project No. G1968-11-02 -7- October 12, 2018 6.2.2 Based on the soil encountered in the previous grading operations for the site, we expect the near surface soil to be "non-expansive" (expansion index of 20 or less) as defined by 2016 California Building Code (CBC) Section 1803.5.3. Table 6.2 presents soil classifications based on the expansion index. Based on the reported results of previous laboratory testing, we expect the on-site materials will possess a "very low" expansion potential (Expansion Index of 20 or less). TABLE 6.2 EXPANSION CLASSIFICATION BASED ON EXPANSION INDEX Expansion Index (El) Expansion Classification 2016 CBC Expansion Classification 0 —20 Very Low Non-Expansive 21-50 Low Expansive Very High 51 -90 Medium 91 -130 High Greater Than 130 6.2.3 Previously reported laboratory water-soluble sulfate content test results indicate an "SO" sulfate severity exposure to concrete structures as defined by 2016 CBC Section 1904 and ACI 318-14 Chapter 19. The presence of water-soluble sulfates is not a visually discernible characteristic; therefore, other soil samples from the site could yield different concentrations. Additionally, over time landscaping activities (i.e., addition of fertilizers 6.2.4 Geocon Incorporated does not practice in the field of corrosion engineering. Therefore, further evaluation by a corrosion engineer may be performed if improvements that could be susceptible to corrosion are planned. 6.3 Seismic Design Criteria 6.3.1 We used the computer program US. Seismic Design Maps, provided by the USGS. Table 6.3.1 summarizes site-specific design criteria obtained from the 2016 California Building Code (CBC; Based on the 2015 International Building Code [IBC] and ASCE 7- 10), Chapter 16 Structural Design, Section 1613 Earthquake Loads. The short spectral response uses a period of 0.2 second. The new and existing building structures and improvements should be designed using a Site Class D. We evaluated the Site Class based on the discussion in Section 1613.3.2 of the 2016 CBC and Table 20.3-1 of ASCE 7-10. The values presented in Table 6.3.1 are for the risk-targeted maximum considered earthquake (MCER). Project No. G1968-11-02 -8- October 12, 2018 TABLE 6.3.1 2016 CBC SEISMIC DESIGN PARAMETERS Parameter Value 2016 CBC Reference Site Class D Table 1613.3.2 NICER Ground Motion Spectral Response 1.070g Figure 16 13.3.1(1) Acceleration - Class B (short), Ss MCER Ground Motion Spectral Response 0.413g Figure 1613.3.1(2) Acceleration — Class B (1 sec), 1 Site Coefficient, FA 1.072 Table 1613.3.3(1) Site Coefficient, Fv 1.587 Table 1613.3 .3(2) Site Class Modified NICER Spectral Response Acceleration (short), SMS 1.147g Section 1613.3.3 (Eqn 16-37) Site Class Modified NICER Spectral Response Acceleration (1 sec), SM! 0.655g Section 16 13.3.3 (Eqn 16-38) 5% Damped Design Spectral Response Acceleration (short), So5 0.765g Section 1613.3.4 (Eqn 16-39) 5% Damped Design Spectral Response Acceleration (1 sec), SD! 0.437g Section 1613.3.4 (Eqn 16-40) 6.3.2 Table 6.3.2 presents additional seismic design parameters for projects located in Seismic Design Categories of D through F in accordance with ASCE 7-10 for the mapped maximum considered geometric mean (MCEG). TABLE 6.3.2 2016 CBC SITE ACCELERATION DESIGN PARAMETERS Parameter Value ASCE 7-10 Reference Mapped MCEG Peak Ground Acceleration, PGA 0.422g Figure 22-7 Site Coefficient, FPGA 1.078 Table 11.8-1 Site Class Modified MCEG Peak Ground Acceleration, PGAM 0.455g Section 11.8.3 (Eqn 11.8-1) 6.3.3 Conformance to the criteria in Tables 6.3.1 and 6.3.2 for seismic design does not constitute any kind of guarantee or assurance that significant structural damage or ground failure will not occur if a maximum level earthquake occurs. The primary goal of seismic design is to protect life and not to avoid all damage, since such design may be economically prohibitive. Project No. G1968-11-02 - 9 - October 12, 2018 6.3.4 The project structural engineer and architect should evaluate the appropriate Risk Category and Seismic Design Category for the planned structures. The values presented herein assume a Rick Category of I, II or III and resulting in a Seismic Design Category D. 6.4 Temporary Excavations 6.4.1 The recommendations included herein are provided for stable excavations. It is the responsibility of the contractor to provide a safe excavation during the construction of the proposed project. 6.4.2 The stability of the excavations is dependent on the design and construction of the shoring system and site conditions. Therefore, Geocon Incorporated cannot be responsible for site safety and the stability of the proposed excavations. It is the responsibility of the contractors during excavations to follow all applicable safety standards and industry protocols when performing excavations during the construction of the proposed project. 6.4.3 Temporary excavations should be made in conformance with OSHA requirements. The properly compacted fill can be considered a Type B soil (Type C soil if seepage or groundwater is encountered) and the formational materials (without weak bedding planes) should be considered a Type A soil (Type B soil if seepage or groundwater is encountered) in accordance with OSHA requirements. In general, special shoring requirements may not be necessary if temporary excavations will be less than 4 feet in height. Temporary excavations greater than 4 feet in height, however, should be sloped back at an appropriate inclination. These excavations should not be allowed to become saturated or to dry out. Surcharge loads should not be permitted to a distance equal to the height of the excavation from the top of the excavation. The top of the excavation should be a minimum of 15 feet from the edge of existing improvements. Excavations steeper than those recommended or closer than 15 feet from an existing surface improvement should be shored in accordance with applicable OSHA codes and regulations. 6.5 Grading 6.5.1 Grading should be performed in accordance with the recommendations presented herein. We should perform the testing and observation services during the grading and improvement operations. 6.5.2 Prior to commencing grading, a preconstruction conference should be held at the site with the owner or developer, grading contractor, city inspector, civil engineer and geotechnical engineer in attendance. Special soil handling requirements can be discussed at that time. Project No. G1968-11-02 -10- October 12, 2018 6.5.3 Site preparation should begin with the removal of vegetation and debris and the demolition of the existing hardscape and landscaping in the area of the proposed improvements. The depth of removal should be such that material to be used as fill is generally free of organic matter. Material generated during stripping operations should be exported from the site. 6.5.4 We expect that the near surface soil will consist of previously compacted fill that will be loose and dry or locally saturated in landscape and basin areas. The upper 1 to 3 feet of the existing soil should be removed below existing grade with the depth dependent on its density and moisture content prior to placing new fill soil. The bottom of the removal should be processed, moisture conditioned as necessary and properly compacted within the limits of proposed improvements. We should be present during removals to evaluate the limits of the remedial grading. Deeper removals may be required where relatively soft, dry, or saturated soil is encountered. 6.5.5 Excavated soil generally free of deleterious debris can be placed as new fill by compacting in layers to the design finish-grade elevations. Fill and backfill soil should be compacted to a dry density of at least 90 percent of laboratory maximum dry density near to slightly above optimum moisture content as determined by ASTM Test Procedure D 1557. 6.5.6 Import fill (if necessary) should consist of granular materials with a "very low" to "low" expansion potential (El of 50 or less), free of deleterious material or rock larger than 3 inches, and should be compacted as recommended herein. Geocon Incorporated should be notified of the import soil source and should perform laboratory testing of import soil prior to its arrival at the site to determine its suitability as fill material. 6.6 Shallow Foundations and Concrete Slabs-On-Grade Recommendations 6.6.1 The proposed new buildings and building expansions can be supported on shallow foundations bearing on compacted fill. Foundations should consist of continuous strip footings and/or isolated spread footings. Continuous footings should be at least 12 inches wide and extend at least 24 inches below lowest adjacent pad grade. Isolated spread footings should have a minimum width of 2 feet and should also extend at least 24 inches below lowest adjacent pad grade. A wall/column footing dimension detail is presented on C) Figure 3. 6.6.2 Steel reinforcement for continuous footings should consist of at least four No. 5 steel reinforcing bars placed horizontally in the footings, two near the top and two near the bottom. Steel reinforcement for the spread footings should be designed by the project structural engineer. Project No. G1968-11-02 - 11 - October 12, 2018 6.6.3 Footings for buildings and retaining walls should be deepened such that the bottom outside edge of the footing is at least 7 feet horizontally from the face of slopes. 6.6.4 The recommendations herein are based on soil characteristics only (El of 50 or less) and are not intended to replace reinforcement required for structural considerations. 6.6.5 The recommended allowable bearing capacity for foundations with minimum dimensions described herein and bearing in compacted fill is 2,000 pounds per square foot (psf). The allowable soil bearing pressure may be increased by an additional 500 psf for each additional foot of depth and width, to a maximum allowable bearing capacity of 4,000 psf. The values presented herein are for dead plus live loads and may be increased by one-third when considering transient loads due to wind or seismic forces. 6.6.6 We estimate the total and differential settlements under the imposed allowable loads to be about 1 inch and V2 inch, respectfully, based on a 5-foot square footing. 6.6.7 New concrete floor slabs should possess a thickness of at least 5 inches and reinforced with a minimum of No. 3 steel reinforcing bars at 18 inches on center in both horizontal directions placed in the middle of the slab based on soil conditions. The structural engineer should design the steel required for the planned expansion. 6.6.8 Slabs that may receive moisture-sensitive floor coverings or may be used to store moisture- sensitive materials should be underlain by a vapor retarder. The vapor retarder design should be consistent with the guidelines presented in the American Concrete Institute's (AC!) Guide for Concrete Slabs that Receive Moisture-Sensitive Flooring Materials (AC! 302.2R-06). In addition, the membrane should be installed in accordance with manufacturer's recommendations and ASTM requirements and installed in a manner that prevents puncture. The vapor retarder used should be specified by the project architect or developer based on the type of floor covering that will be installed and if the structure will possess a humidity- controlled environment. 6.6.9 As an alternative to the conventional foundation recommendations, consideration should be given to the use of post-tensioned concrete slab and foundation systems for the support of the proposed structures. The post-tensioned systems should be designed by a structural engineer experienced in post-tensioned slab design and design criteria of the Post-Tensioning Institute (PTI) DC10.5 as required by the 2016 California Building Code (CBC Section. 1808.6.2). Although this procedure was developed for expansive soil conditions, we understand it can also be used to reduce the potential for foundation distress due to differential fill settlement. The post-tensioned design should incorporate the Project No. G1968-11-02 -12- October 12, 2018 geotechnical parameters presented on Table 6.6. The parameters presented in Table 6.6 are based on the guidelines presented in the PT!, DC 10.5 design manual. TABLE 6.6 POST-TENSIONED FOUNDATION SYSTEM DESIGN PARAMETERS Post-Tensioning Institute (PT!) DC10.5 Design Parameters Value Thomthwaite Index -20 Equilibrium Suction 3.9 Edge Lift Moisture Variation Distance, em (feet) 4.9 Edge Lift, YM (inches) 1.58 Center Lift Moisture Variation Distance, CM (feet) 9.0 Center Lift, YM (inches) 0.66 6.6.10 If the structural engineer proposes a post-tensioned foundation design method other than the 2016 CBC: The criteria presented in Table 6.6 are still applicable. Interior stiffener beams should be used. The width of the perimeter foundations should be at least 12 inches. The perimeter footing embedment depths should be at least 24 inches. The embedment depths should be measured from the lowest adjacent pad grade. 6.6.1 1 Our experience indicates post-tensioned slabs are susceptible to excessive edge lift, regardless of the underlying soil conditions. Placing reinforcing steel at the bottom of the perimeter footings and the interior stiffener beams may mitigate this potential. Current PT! design procedures primarily address the potential center lift of slabs but, because of the placement of the reinforcing tendons in the top of the slab, the resulting eccentricity after tensioning reduces the ability of the system to mitigate edge lift. The structural engineer should design the foundation system to reduce the potential of edge lift occurring for the proposed structures. 6.6.12 The foundations for the post-tensioned slabs should be embedded in accordance with the recommendations of the structural engineer. If a post-tensioned mat foundation system is planned, the slab should possess a thickened edge with a minimum width of 12 inches and extend below the clean sand or crushed rock layer. 6.6.13 During the construction of the post-tension foundation system, the concrete should be placed monolithically. Under no circumstances should cold joints form between the Project No. G1968-11-02 - 13- October 12, 2018 footings/grade beams and the slab during the construction of the post-tension foundation system unless designed by the project structural engineer. 6.6.14 Isolated footings, if present, should have the minimum embedment depth and width recommended for conventional foundations. The use of isolated footings, which are located beyond the perimeter of the building and support structural elements connected to the building, are not recommended. Where this condition cannot be avoided, the isolated footings should be connected to the building foundation system with grade beams. 6.6.15 Consideration should be given to using interior stiffening beams and connecting isolated footings and/or increasing the slab thickness. In addition, consideration should be given to connecting patio slabs, which exceed 5 feet in width, to the building foundation to reduce the potential for future separation to occur. 6.6.16 The bedding sand thickness should be determined by the project foundation engineer, architect, and/or developer. It is common to have 3 inches of sand for 5-inch thick slabs in the southern California region. However, we should be contacted to provide recommendations if the bedding sand is thicker than 6 inches. The foundation design engineer should provide appropriate concrete mix design criteria and curing measures to assure proper curing of the slab by reducing the potential for rapid moisture loss and subsequent cracking and/or slab curl. We suggest that the foundation design engineer present the concrete mix design and proper curing methods on the foundation plans. It is critical that the foundation contractor understands and follows the recommendations presented on the foundation plans. 6.6.17 Foundation excavations should be observed by the geotechnical engineer (a representative of Geocon Incorporated) prior to the placement of reinforcing steel to check that the exposed soil conditions are similar to those expected and that they have been extended to the appropriate bearing strata. If unexpected soil conditions are encountered, foundation modifications may be required. 6.6.18 Special subgrade presaturation is not deemed necessary prior to placing concrete; however, the exposed foundation and slab subgrade soil should be moisturized to maintain a moist condition as would be expected in any such concrete placement. 6.6.19 The foundation and concrete slab-on-grade recommendations are based on soil support characteristics only. The project structural engineer should evaluate the structural requirements of the concrete slabs for supporting expected loads. Project No. G 1968-11-02 -14- October 12, 2018 6.6.20 Concrete slabs should be provided with adequate crack-control joints, construction joints and/or expansion joints to reduce unsightly shrinkage cracking. The design of joints should consider criteria of the American Concrete Institute when establishing crack-control spacing. Additional steel reinforcing, concrete admixtures and/or closer crack control joint spacing should be considered where concrete-exposed finished floors are planned. 6.6.21 The recommendations of this report are intended to reduce the potential for cracking of slabs due to expansive soil (if present), differential settlement of existing soil or soil with varying thicknesses. However, even with the incorporation of the recommendations presented herein, foundations, stucco walls, and slabs-on-grade placed on such conditions may still exhibit some cracking due to soil movement and/or shrinkage. The occurrence of concrete shrinkage cracks is independent of the supporting soil characteristics. Their occurrence may be reduced and/or controlled by limiting the slump of the concrete, proper concrete placement and curing, and by the placement of crack control joints at periodic intervals, in particular, where re-entrant slab corners occur. 6.6.22 Geocon Incorporated should be consulted to provide additional design parameters as required by the structural engineer. 6.7 Concrete Flatwork 6.7.1 Exterior concrete flatwork not subject to vehicular traffic should be constructed in accordance with the recommendations herein. Slab panels should be a minimum of 4 inches thick and, when in excess of 8 feet square, should be reinforced with 6 x 6 - W2.9/W2.9 (6 x 6 - 6/6) welded wire mesh or No. 3 reinforcing bars spaced at 18 inches on center in both directions to reduce the potential for cracking. In addition, concrete flatwork should be provided with crack control joints to reduce and/or control shrinkage cracking. Crack control spacing should be determined by the project structural engineer based upon the slab thickness and intended usage. Criteria of the American Concrete Institute (ACI) should be taken into consideration when establishing crack control spacing. Subgrade soil for exterior slabs not subjected to vehicle loads should be compacted in accordance with criteria presented in the grading section prior to concrete placement. Subgrade soil should be properly compacted and the moisture content of subgrade soil should be checked prior to placing concrete. 6.7.2 Even with the incorporation of the recommendations within this report, the exterior concrete flatwork has a likelihood of experiencing some movement due to swelling or settlement; therefore, the reinforcing steel should overlap continuously in flatwork to reduce the potential for vertical offsets within flatwork. Project No. G1968-11-02 _15- - October 12, 2018 6.7.3 Where exterior flatwork abuts the structure at entrant or exit points, the exterior slab should be dowelled into the structure's foundation stemwall. This recommendation is intended to reduce the potential for differential elevations that could result from differential settlement or minor heave of the flatwork. Dowelling details should be designed by the project structural engineer. 6.8 Retaining Walls 6.8.1 Retaining walls not restrained at the top and having a level backfill surface should be designed for an active soil pressure equivalent to the pressure exerted by a fluid density of 35 pounds per cubic foot (pcf). Where the backfill will be inclined at 2:1 (horizontal to vertical), we recommend an active soil pressure of 50 pcf. Soil with an expansion index (El) of greater than 50 should not be used as backfill material behind retaining walls. 6.8.2 Unrestrained walls are those that are allowed to rotate more than 0.001H (where H equals the height of the retaining portion of the wall) at the top of the wall. Where walls are restrained from movement at the top (at-rest condition), an additional uniform pressure of 7H psf should be added to the active soil pressure for walls 8 feet or less. For walls greater than 8 feet tall, an additional uniform pressure of 1311 psf should be applied to the wall starting at 8 feet from the top of the wall to the base of the wall. For retaining walls subject to vehicular loads within a horizontal distance equal to two-thirds the wall height, a surcharge equivalent to 2 feet of fill soil should be added. 6.8.3 The structural engineer should determine the Seismic Design Category for the project in accordance with Section 1613.3.5 of the 2016 CBC or Section 11.6 of ASCE 7-10. For structures assigned to Seismic Design Category of D, E, or F, retaining walls that support more than 6 feet of backfill should be designed with seismic lateral pressure in accordance with Section 1803.5.12 of the 2016 CBC. The seismic load is dependent on the retained height where H is the height of the wall, in feet, and the calculated loads result in pounds per square foot (psf) exerted at the base of the wall and zero at the top of the wall. A seismic load of 16H should be used for design. We used the peak ground acceleration adjusted for Site Class effects, PGAM, of 0.455g calculated from ASCE 7-10 Section 11.8.3 and applied a pseudo-static coefficient of 0.3. Figure 4 presents a retaining wall loading diagram. 6.8.4 The retaining walls may be designed using either the active and restrained (at-rest) loading condition or the active and seismic loading condition as suggested by the structural engineer. Typically, it appears the design of the restrained condition for retaining wall loading may be adequate for the seismic design of the retaining walls. However, the active Project No. G1968-11-02 -16- October 12, 2018 earth pressure combined with the seismic design load should be reviewed and also considered in the design of the retaining walls. 6.8.5 Drainage openings through the base of the wall (weep holes) should not be used where the seepage could be a nuisance or otherwise adversely affect the property adjacent to the base of the wall. The recommendations herein assume a properly compacted granular (El of 50 or less) free-draining backfill material with no hydrostatic forces or imposed surcharge load. Figure 5 presents a typical retaining wall drainage detail. If conditions different than those described are expected, or if specific drainage details are desired, Geocon Incorporated should be contacted for additional recommendations. 6.8.6 In general, wall foundations having a minimum depth and width of 1 foot may be designed for an allowable soil bearing pressure of 2,000 psf. The allowable soil bearing pressure may be increased by an additional 300 psf for each additional foot of depth and width, to a maximum allowable bearing capacity of 3,000 psf. The proximity of the foundation to the top of a slope steeper than 3:1 could affect the allowable soil bearing pressure. Therefore, retaining wall foundations should be deepened such that the bottom outside edge of the footing is at least 7 feet horizontally from the face of the slope. 6.8.7 The recommendations presented herein are generally applicable to the design of rigid concrete or masonry retaining walls. In the event that other types of walls (such as mechanically stabilized earth [MSE] walls, soil nail walls, or soldier pile walls) are planned, Geocon Incorporated should be consulted for additional recommendations. 6.8.8 Unrestrained walls will move laterally when backfihled and loading is applied. The amount of lateral deflection is dependent on the wall height, the type of soil used for backfill, and loads acting on the wall. The retaining walls and improvements above the retaining walls should be designed to incorporate an appropriate amount of lateral deflection as determined by the structural engineer. 6.8.9 Soil contemplated for use as retaining wall backfill, including import materials, should be identified in the field prior to backfill. At that time, Geocon Incorporated should obtain samples for laboratory testing to evaluate its suitability. Modified lateral earth pressures may be necessary if the backfill soil does not meet the required expansion index or shear strength. City or regional standard wall designs, if used, are based on a specific active lateral earth pressure and/or soil friction angle. In this regard, on-site soil to be used as backfill may or may not meet the values for standard wall designs. Geocon Incorporated should be consulted to assess the suitability of the on-site soil for use as wall backfill if standard wall designs will be used. Project No. G1968-11-02 - 17- October 12, 2018 6.9 Lateral Loading 6.9.1 To resist lateral loads, a passive pressure exerted by an equivalent fluid weight of 300 pounds per cubic foot (pcf) should be used for the design of footings or shear keys poured neat in compacted fill. The passive pressure assumes a horizontal surface extending at least 5 feet, or three times the surface generating the passive pressure, whichever is greater. The upper 12 inches of material in areas not protected by floor slabs or pavement should not be included in design for passive resistance. 6.9.2 If friction is to be used to resist lateral loads, an allowable coefficient of friction between soil and concrete of 0.35 should be used for design. 6.9.3 The passive and frictional resistant loads can be combined for design purposes. The lateral passive pressures may be increased by one-third when considering transient loads due to wind or seismic forces. 6.10 Preliminary AC and PCC Pavement Recommendations 6.10.1 We calculated the flexible, asphalt concrete (AC) pavement sections in general conformance with the Caltrans Method of Flexible Pavement Design (Highway Design Manual, Section 608.4) using a Traffic Index (TI) of 5.0 and 5.5 for the private drives and parking stalls, respectively. The final pavement sections should be based on the R-Value of the subgrade soil encountered at final subgrade elevation. We used an R-Value of 20 for the subgrade soil based on previous laboratory test results and an R-Value of 78 for base materials, respectively, for the purposes of this preliminary analysis. Table 6. 10.1 presents the preliminary flexible pavement sections. TABLE 6.10.1 PRELIMINARY FLEXIBLE PAVEMENT SECTION Assumed Assumed Asphalt Class 2 Location Traffic Index Subgrade Concrete (AC) Aggregate Base R-Value (inches) (inches) Parking Stalls 5.0 1 20 1 4.0 1 5.0 Driveways 5.5 1 20 1 4.0 16.0 6.10.2 Prior to placing base materials, the upper 12 inches of the subgrade soil should be scarified, moisture conditioned as necessary, and recompacted to a dry density of at least 95 percent of the laboratory maximum dry density near to slightly above optimum moisture content as determined by ASTM D 1557. Similarly, the base material should be compacted to a dry Project No. G1968-11-02 -18- October 12, 2018 density of at least 95 percent of the laboratory maximum dry density near to slightly above optimum moisture content. Asphalt concrete should be compacted to a density of at least 95 percent of the laboratory Hveem density in accordance with ASTM D 2726. 6.10.3 A rigid Portland cement concrete (PCC) pavement section can also be used for vehicular pavement. We calculated the rigid pavement section in general conformance with the procedure recommended by the American Concrete Institute report ACT 330R-08 Guide for Design and Construction of Concrete Parking Lots using the parameters presented in Table 6.10.2. TABLE 6.10.2 RIGID PAVEMENT DESIGN PARAMETERS Design Parameter Design Value Modulus of subgrade reaction, k 50 pci Modulus of rupture for concrete, MR 500 psi Traffic Category, TC A and B Average daily truck traffic, ADTF 10 and 25 6.10.4 Based on the criteria presented herein, the PCC pavement sections should have a minimum thickness as presented in Table 6.10.3. TABLE 6.10.3 RIGID PAVEMENT RECOMMENDATIONS Location Portland Cement Concrete (inches) Parking Stalls (TC = A) 6.0 Driveways (TC = B) 7.0 6.10.5 The PCC pavement should be placed over subgrade soil that is compacted to a dry density of at least 95 percent of the laboratory maximum dry density near to slightly above optimum moisture content. This pavement section is based on a minimum concrete compressive strength of approximately 3,000 psi (pounds per square inch). Base material will not be required beneath concrete improvements. 6.10.6 A thickened edge or integral curb should be constructed on the outside of concrete slabs subjected to wheel loads. The thickened edge should be 1.2 times the slab thickness or a minimum thickness of 2 inches, whichever results in a thicker edge, and taper back to the Project No. G1968-ll-02 -19- October 12, 2018 recommended slab thickness 4 feet behind the face of the slab (e.g., a 7-inch-thick slab would have a 9-inch-thick edge). Reinforcing steel will not be necessary within the concrete for geotechnical purposes with the possible exception of dowels at construction joints as discussed herein. 6.10.7 To control the location and spread of concrete shrinkage cracks, crack-control joints (weakened plane joints) should be included in the design of the concrete pavement slab. Crack-control joints should not exceed 30 times the slab thickness with a maximum spacing of 15 feet for the slabs thicker than 6 inches (e.g. a 7-inch-thick slab would have a 15-foot spacing pattern), and should be sealed with an appropriate sealant to prevent the migration of water through the control joint to the subgrade materials. The depth of the crack-control joints should be determined by the referenced AC! report. 6.10.8 To provide load transfer between adjacent pavement slab sections, a butt-type construction joint should be constructed. The butt-type joint should be thickened by at least 20 percent at the edge and taper back at least 4 feet from the face of the slab. As an alternative to the butt-type construction joint, dowelling can be used between construction joints for pavements of 7 inches or thicker. As discussed in the referenced AC! guide, dowels should consist of smooth, 1-inch-diameter reinforcing steel 14 inches long embedded a minimum of 6 inches into the slab on either side of the construction joint. Dowels should be located at the midpoint of the slab, spaced at 12 inches on center and lubricated to allow joint movement while still transferring loads. In addition, tie bars should be installed at the as recommended in Section 3.8.3 of the referenced ACI guide. The structural engineer should provide other alternative recommendations for load transfer. 6.10.9 The performance of pavement is highly dependent on providing positive surface drainage away from the edge of the pavement. Ponding of water on or adjacent to the pavement will likely result in pavement distress and subgrade failure if not mitigated. Drainage from landscaped areas should be directed to controlled drainage structures. Landscape areas adjacent to the edge of asphalt pavements are not recommended due to the potential for surface or irrigation water to infiltrate the underlying permeable aggregate base and cause distress. Where such a condition cannot be avoided, consideration should be given to incorporating measures that will significantly reduce the potential for subsurface water migration into the aggregate base. If planter islands are planned, the perimeter curb should extend at least 6 inches. Project No. G1968-11-02 -20- October 12, 2018 6.11 Interlocking Pervious Concrete Paver Recommendations 6.11.1 We understand vehicular pervious concrete payers will be installed on at the western terminus of Drive A. The concrete paver thickness should not be less than 31/8 inches. The payers should be installed and maintained in accordance with the manufacturer's recommendations. In addition, the concrete payers should be installed in a pattern acceptable for vehicular traffic. A subdrain should be installed within the base materials at the low point of the subgrade as discussed herein. 6.11.2 We calculated the concrete paver pavement sections in general conformance with the Caltrans Method of Flexible Pavement Design (Highway Design Manual, Section 608.4). We used an R-Value of 20 for the subgrade soil for our analysis and an R-Value of 78 for the base materials per Caltrans specifications. 6.11.3 We understand that Class 2 aggregate base will be placed below the concrete pavers. We calculated the base section based on an equivalent asphalt concrete section equal to the thickness of the concrete vehicular paver (about 3 inches or 80 mm) in accordance with the Interlocking Concrete Pavement Institute, Tech Spec Number 4. The paver pavement sections can be increased as required by manufacturer's recommendations. Table 6.11 presents the recommended interlocking paver pavement sections. TABLE 6.11 INTERLOCKING PAVER PAVEMENT SECTIONS Estimated Bedding Minimum Location Traffic Subgrade Paver Sand Thickness Class 2 Aggregate Index R-Value Thickness Base Thickness (inches) (inches) (inches) Driveway 5.5 20 3 Vs 1-2 9 6.11.4 Prior to placing base materials, the upper 12 inches of the subgrade soil should be scarified, moisture conditioned as necessary, and recompacted to a dry density of at least 95 percent of the laboratory maximum dry density near to slightly above optimum moisture content as determined by ASTM D 1557. Similarly, the base material should be compacted to a dry density of at least 95 percent of the laboratory maximum dry density near to slightly above optimum moisture content. 6.11.5 The property owner should be informed by the manufacturer of their responsibility for the paver maintenance program. In addition, payers tend to shift vertically and horizontally during the life of the pavement and should be expected. The payers normally require a Project No. G1968-11-02 -21 - October 12, 2018 concrete border to reduce the magnitude of lateral movement from traffic. The concrete border surrounding the payers should be embedded at least 6 inches from finish grade surface. We understand that the space between concrete payers will be pervious to allow water infiltration into the underlying base materials. The recommendations for draining the base of water as discussed herein should be included in design. 6.11.6 Concrete pedestrian payers can be used at the site as long as surface runoff is not concentrated toward the permeable paver areas. The pedestrian concrete payers can also be designed as permeable if desired with the addition of a subdrain placed within the base. Therefore, the bottom of permeable paver areas do not need to be lined. 6.11 .'7 Based on the Interlocking Concrete Pavement Institute (ICPI), the payers should possess a minimum thickness of 60 millimeters overlying 1 to 1 '/2 inch of sand. The sand should be underlain by at least 4 inches of Class 2 aggregate base or #57 aggregate in accordance with ASTM C 33 and in accordance with the manufacturer's recommendations. The aggregate section can be thickened to increase the water capacity as required by the project civil engineer. 6.11.8 Prior to placing aggregate materials, the subgrade soil should be scarified, moisture conditioned as necessary, and recompacted to a dry density of at least 90 percent of the laboratory maximum dry density near to slightly above optimum moisture content as determined by ASTM D 1557. The depth of compaction should be at least 12 inches. Similarly, the aggregate base materials should be compacted to a dry density of at least 95 percent of the laboratory maximum dry density near to slightly above optimum moisture content. 6.11.9 The subgrade of the pervious payers should be graded to allow water to flow to a subdrain at a minimum gradient of 2 percent. A subdrain should be installed within the base materials at the low point of the subgrade to reduce the potential for water to build up within the paving section. The subdrain can be elevated above the subgrade a maximum of 3 inches within the base section. The subdrain should be connected to an approved drainage device. The subdrain should consist of at least 3-inch diameter perforated Schedule 40, PVC pipe. 6.11. 10 A continuous impermeable liner or rigid concrete cutoff wall should be installed along the sides of the pervious paver section to prevent water migration. The sidewall liner is not required if the concrete border wall is installed to an elevation of the bottom of the base materials. The sidewall liner should consist of a high density polyethylene (HDPE) with a minimum thickness of 15 mil or equivalent with the liner or concrete cutoff wall extending to the subgrade elevation. The liner/barrier should be sealed at the connections in accordance Project No. G1968-11-02 -22- October 12, 2018 with manufacturer recommendations and should be properly waterproofed at the drain connection. 6.11.11 The performance of pavement is highly dependent on providing positive surface drainage away from the edge of the pavement. Ponding of water on or adjacent to the pavement will likely result in pavement distress and subgrade failure. Drainage from landscaped areas should be directed to controlled drainage structures. Landscape areas adjacent to the edge of asphalt pavements are not recommended due to the potential for surface or irrigation water to infiltrate the underlying permeable aggregate base and cause distress. Where such a condition cannot be avoided, consideration should be given to incorporating measures that will significantly reduce the potential for subsurface water migration into the aggregate base. If planter islands are planned, the perimeter curb should extend at least 6 inches below the level of the base materials. 6.12 Site Drainage and Moisture Protection 6.12.1 Adequate site drainage is critical to reduce the potential for differential soil movement, erosion and subsurface seepage. Under no circumstances should water be allowed to pond adjacent to footings. The site should be graded and maintained such that surface drainage is directed away from structures in accordance with 2016 CBC 1804.3 or other applicable standards. In addition, surface drainage should be directed away from the top of slopes into swales or other controlled drainage devices. Roof and pavement drainage should be directed into conduits that carry runoff away from the proposed structures. 6.12.2 In the case of building walls retaining landscaping areas, a waterproofing system should be used on the wall and joints, and a Miradrain drainage panel (or similar) should be placed over the waterproofing. The wall drains should extend to groundwater levels near the base of the wall. The project architect or civil engineer should provide detailed specifications on the plans for all waterproofing and drainage. 6.12.3 Underground utilities should be leak free. Utility and irrigation lines should be checked periodically for leaks, and detected leaks should be repaired promptly. Detrimental soil movement could occur if water is allowed to infiltrate the soil for prolonged periods of time. 6.12.4 Two new biofiltration basins (BMP 2 and 3) are proposed at the site and should be lined in accordance with a "No Infiltration" design using an impermeable liner that has sufficient strength and thickness to resist puncture during construction and use. However, the existing biofiltration basin (BMP 1) is being renovated to meet current stormwater standards and Project No. G1968-11-02 -23- October 12, 2018 will not need to be lined. The liner should be placed on the sides and bottom of the new basins to prevent lateral migration of water. 6.13 Foundation Plan Review 6.13.1 Geocon Incorporated should review the foundation plans for the project prior to final design submittal to evaluate if additional analyses and/or recommendations are required. Project No. G1968-11-02 -24- October 12, 2018 LIMITATIONS AND UNIFORMITY OF CONDITIONS The firm that performed the geotechnical investigation for the project should be retained to provide testing and observation services during construction to provide continuity of geotechnical interpretation and to check that the recommendations presented for geotechnical aspects of site development are incorporated during site grading, construction of improvements, and excavation of foundations. If another geotechnical firm is selected to perform the testing and observation services during construction operations, that firm should prepare a letter indicating their intent to assume the responsibilities of project geotechnical engineer of record. A copy of the letter should be provided to the regulatory agency for their records. In addition, that firm should provide revised recommendations concerning the geotechnical aspects of the proposed development, or a written acknowledgement of their concurrence with the recommendations presented in our report. They should also perform additional analyses deemed necessary to assume the role of Geotechnical Engineer of Record. The recommendations of this report pertain only to the site investigated and are based upon the assumption that the soil conditions do not deviate from those disclosed in the investigation. If any variations or undesirable conditions are encountered during construction, or if the proposed construction will differ from that anticipated herein, Geocon Incorporated should be notified so that supplemental recommendations can be given. The evaluation or identification of the potential presence of hazardous or corrosive materials was not part of the scope of services provided by Geocon Incorporated. This report is issued with the understanding that it is the responsibility of the owner or his 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. The findings of this report are valid as of the present date. However, changes in the conditions of a property can occur with the passage of time, whether they be due to natural processes or the works of man on this or adjacent properties. In addition, changes in applicable or appropriate standards may occur, whether they result from legislation or the broadening of knowledge. Accordingly, the findings of this report may be invalidated wholly or partially by changes outside our control. Therefore, this report is subject to review and should not be relied upon after a period of three years. Project No. G1968-11-02 October 12, 2018 ~ :~ ' I" ITE~'i HE GEOGRAPHICAL INFORMATION MADE AVAILABLE FOR DISPLAY WAS PROVIDED BY 000GLE EARTH, SUBJECT TO A LICENSING AGREEMENT THE INFORMATION IS FOR ILLUSTRATIVE PURPOSES ONLY; IT IS NOT INTENDED FOR CLIENTS USE OR RELIANCE A 'ID SHALL NOT BE REPRODUCED BY CLIENT CLIENT SHALL INDEMNIFY, DEFEND AND HOLD HARMLESS GEOCON FROM ANY LIABILITY INCURRED AS A RESULT OF SUCH USE OR RELIANCE BY CLIENT. NO SCALE VICINITY MAP GEOCON INCORPORATED f GEOTECHNICAL U ENVIRONMENTAL U MATERIALS 6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121- 2974 PHONE 858 558-6900 - FAX 858 558-6159 JH/CW DSK/GTYPD COASTLINE COMMUNITY CHURCH EXPANSION 2215 CALLE BARCELONA CARLSBAD, CALIFORNIA DATE 10- 12- 2018 PROJECT NO. G1968 - 11 -02 FIG. 1 Plotted - 0/12/2018 7:45AM I By:ALVIN LADRILLONO I File LocationY:11_GE0TECH\G1000/G1968-1 1-02/201 8/2018-10-12\DETAILS\01968-11-02 VicootyMap. CONCRETE SLAB .4: 4 4 e PD GRADE SAND AND VAPOR 4.4 RETARDER IN . a ..,a.. ACCORDANCE W1THACI •. . / < Z... I— Q : : FOOTING* WIDTH .44 4' a a .44 SAND AND VAPOR J/ 4 a a - / RETARDERIN e a ACCORDANCE WTHACI 4 a a - - a. ow 4 a 4 a O LL ;4 :- FOOTING WIDTH* *SEE REPORT FOR FOUNDATION WIDTH AND DEPTH RECOMMENDATION NO SCALE I WALL / COLUMN FOOTING DIMENSION DETAIL I GEOCON (OD INCORPORATED GEOTECHNICAL U ENVIRONMENTAL 11111-MATERIALS 6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121- 2974 PHONE 858 558-6900 - FAX 858 558-6159 JH/CW DSK/GTYPD COASTLINE COMMUNITY CHURCH EXPANSION 2215 CALLE BARCELONA CARLSBAD, CALIFORNIA I DATE 10-12- 2018 I PROJECT NO. G1968 -11 -02 I FIG. 3 I Plotted: 1011212018 7:44AM I By:ALVIN LADRILLONO I File Location:Y:\1_GEOTECH\G1OOO\G1968-11-O2\2O18\2O18-1O-12DETAlLS\Wall-Colurnn Footing Dimension Detail (COLFOOT2).dwg AT-REST! IF PRESENT. ACTIVE SEISMIC RESTRAINED PRESSURE (IF REQUIRED) (IF REQUIRED) - \ H8' £ 7K \Apsf \ ._i16Hpsf - RETAINING WALL-. - \ - H(Feet) \ 13Hpsf C \ C\ C C H>8' C SLAB C C C \ C \ FOOTING NOTES: 1 A SURCHARGE OF 2 FEET OF SOIL (250 PSF VERTICAL LOAD) SHOULD BE ADDED TO THE DESIGN OF THE WALL WHERE TRAFFIC LOADS ARE WITHIN A HORIZONTAL DISTANCE EQUAL TO 4 THE WALL HEIGHT. OTHER SURCHARGES SHOULD BE APPLIED, AS APPLICABLE. 2.....EXPANSION INDEX GREATER THAN 50/90 SHOULD NOT BE USED FOR WALL BACKFILL PER REFORT. 3 RETAINING WALLS SHOULD BE PROPERLY DRAINED AND WATER PROOFED. 4.....THE PROJECT STRUCTURAL ENGINEER SHOULD EVALUATE THE WALLS LOADING COMBINATIONS. NO SCALE RETAINING WALL LOADING DIAGRAM ACTIVE PRESSURE, A (psf) EXPANSION INDEX, El LEVEL BACKFILL 2:1 SLOPING BACKFILL E1050 35 50 EIss90 40 55 GEOCON (07,%o INCORPORATED GEOTECHNICAL • ENVIRONMENTAL • MATERIALS 6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121- 2974 PHONE 858 558-6900 - FAX 858 558-6159 JH/CW DSK/GTYPD COASTLINE COMMUNITY CHURCH EXPANSION 2215 CALLE BARCELONA CARLSBAD, CALIFORNIA DATE 10-12-2018 PROJECT NO. G1 968 - 11 -02 FIG. 4 plotted:10/12/2018 7:42AM I By:ALVIN LADRILLONO I File Location:V:\1_GEOTECH\G1000\G1968-11-02\2018\ 018 10-12\DETAILS\Retainu,g Wall Loading Diagram (RWLD-NoGroundwater).dwg CONCRETE BROWDITCH PROPOSED RETAINING WALL GROUND SURFACE PROPERLY COMPACTED - BACKFILL 13ACKCU1 ,'—.......TEMPORARY WATER PROOFING _ PER OSHA PER ARCHITECT 3 H MIRAFI 140N FILTER FABRIC - (OR EQUIVALENT) :;.e.. OPEN GRADED 1" MAX. AGGREGATE _..\ 3ROUNDSURFACE Li FOOTING 4' DIA. PERFORATED SCHEDULE L-1 40 PVC PIPE EXTENDED TO APPROVED OUTLET 12' CONCRETE ,.—GROUND SURFACE BROWDITCH RETAINING WALL WATER PROOFING PER ARCHITECT DRAINAGE PANEL - _- (MIRAORAIN 6000 OR EQUIVALENT) 2/3 H 12" -I 314 CRUSHED ROCK - ,./(1 CU.FTJFT.) PROPOSED ,—FILTER FABRIC ENVELOPE GRADE\ ( MIRAFI 140N OR _____ EQUIVALENT FOOTING1 N_ 4" DIA. SCHEDULE 40 I PERFORATED PVC PIPE Llwl OR TOTAL DRAIN EXTENDED TO APPROVED OUTLET NOTE: DRAIN SHOLLD BE UNIFORMLY SLOPED TO GRAVITY OUTLET OR TO A SUMP WHERE WATER CAN BE REMOVED BY PUMPING CONCRETE BROWDITCH GROUND SURFACE RETAINING WALL f WATER PROOFING - PER ARCHITECT 2/3H DRAINAGE PANEL (MIRADRAIN 6000 OR EQUIVALENT) 4" DIA. SCHEDULE 40 PROPOSED PERFORATED PVC PIPE GRADEJ OR TOTAL DRAIN EXTENDED TO FOOTINGl APPROVED OUTLET NO SCALE I TYPICAL RETAINING WALL DRAIN DETAIL I GEOCON (4 INCORPORATED GEOTECHNICAL U ENVIRONMENTAL U MATERIALS 6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121- 2974 PHONE 858 558-6900 - FAX 858 558-6159 JH / CW I I DSK/GTYPD COASTLINE COMMUNITY CHURCH EXPANSION 2215 CALLE BARCELONA CARLSBAD, CALIFORNIA I DATE 10-12- 2018 1 PROJECT NO. G1968 -11 -02 1 FIG. 5 Plotted:10/12/2015 7:43AM I By:ALVIN LADRILLONOI File Location:Y:\1_GEOTECH\GI000\G1968-11-02\2018\2018-10.12\DETAILsvrypicaI Retaining Wall Drainage Detail (RWDD7A).dwg LIST OF REFERENCES 2016 California Building Code, California Code of Regulations, Title 24, Part 2, based on the 2015 International Building Code, prepared by California Building Standards Commission, July 2016. ACI 318-14, Building Code Requirements for Structural Concrete and Commentary on Building Code Requirements for Structural Concrete, prepared by the American Concrete Institute, dated September, 2014. Anderson, J. G., T. K. Rockwell, and D. C. Agnew, Past and Possible Future Earthquakes of Significance to the San Diego Region. Earthquake Spectra, 1989, v. 5, no. 2, p. 299-333. ASCE 7-10, Minimum Design Loads for Buildings and Other Structures, Second Printing, April 6, 2011. Boore, D. M., and G. M Atkinson, Ground-Motion Prediction for the Average Horizontal Component of PGA, PGV, and 5%-Damped PSA at Spectral Periods Between 0.01 and 10.0S, Earthquake Spectra, February 2008, Volume 24, Issue 1, pages 99-138. California Department of Conservation, Division of Mines and Geology, Probabilistic Seismic Hazard Assessmentfor the State of California, Open File Report 96-08, 1996. California Geological Survey, Seismic Shaking Hazards in California, Based on the USGS/CGS Probabilistic Seismic Hazards Assessment (PSHA) Model, 2002 (revised April 2003). 10% probability of being exceeded in 50 years. http://redirect.conservation.ca.gov/cgs/rghnilpshamap/pshamain.html Campbell, K. W., Y. Bozorgnia, NGA Ground Motion Model for the Geometric Mean Horizontal Component of PGA, PGV, PGD and 5% Damped Linear Elastic Response Spectra for Periods Ranging from 0.01 to 10 s, Preprint of version submitted for publication in the NGA Special Volume of Earthquake Spectra, February 2008, Volume 24, Issue 1, pages 139-171. Chiou, Brian S. J., and Robert R. Youngs, A NGA Model for the Average Horizontal Component of Peak Ground Motion and Response Spectra, preprint for article to be published in NGA Special Edition for Earthquake Spectra, Spring 2008. Risk Engineering, EZ-FRISK, 2016. USGS computer program, Seismic Hazard Curves and Uniform Hazard Response Spectra, http://earthcivake.usgs.gov/researchlhazmaps/designl. Project No. G1968-11-02 October 12, 2018