PRELIMINARY GEOTECHNICAL INVESTIGATION LITTLE FLOWER HAVEN 8585 LA MESA BOULEVARD LA MESA, CALIFORNIA SILVERGATE DEVELOPMENT,LLC SAN DIEGO, CALIFORNIA

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1 PRELIMINARY GEOTECHNICAL INVESTIGATION LITTLE FLOWER HAVEN 8585 LA MESA BOULEVARD LA MESA, CALIFORNIA PREPARED FOR SILVERGATE DEVELOPMENT,LLC SAN DIEGO, CALIFORNIA NOVEMBER 17, 2016 PROJECT NO. G

2 GROCON INCORPORATED GEOTECHNICAL ENVIRONMENTAL MATERIALSO Project No. G November 17, 2016 Silvergate Development, LLC 4980 North Harbor Drive, Suite 203 San Diego, California Attention: Subject: Mr. Tommy Edmunds PRELIMINARY GEOTECHNICAL INVESTIGATION LITTLE FLOWER HAVEN 8585 LA MESA BOULEVARD LA MESA, CALIFORNIA Dear Mr. Edmunds: In accordance with your authorization of our proposal (LG-16410, dated October 21, 2016), we herein submit the results of our geotechnical investigation for the subject project. We performed our investigation to evaluate the underlying soil and geologic conditions and potential geologic hazards and to assist in the design of the proposed project. We also conducted infiltration testing at several locations. The accompanying report presents the results of our study and conclusions and recommendations pertaining to the geotechnical aspects of the proposed project. The site is considered suitable for the proposed project provided the recommendations of this report are incorporated into the design and construction of the planned 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 Garry W. Cannon CEG 2201 RCE Rodney C. Mikesell GE 2533 GWC:RCM:dmc (2) Addressee 6960 Flanders Drive San Diego, California Telephone Fax

3 TABLE OF CONTENTS 1. PURPOSE AND SCOPE SITE AND PROJECT DESCRIPTION GENERAL GEOLOGY AND GEOLOGIC SETTING SOIL AND GEOLOGIC CONDITIONS Undocumented Fill (Qudf) Stadium Conglomerate (Tst) Weathered Granitic Rock (Kgr) GROUNDWATER GEOLOGIC HAZARDS Faulting and Seismicity Ground Rupture Seiches and Tsunamis Liquefaction Landslides CONCLUSIONS AND RECOMMENDATIONS General Excavation and Soil Conditions Grading Seismic Design Criteria Conventional Shallow Foundations and Slabs-On-Grade Retaining Walls Storm Water Management Site Drainage and Moisture Protection Slope Maintenance Grading and Foundation Plan Review LIMITATIONS AND UNIFORMITY OF CONDITIONS MAPS AND ILLUSTRATIONS Figure 1, Vicinity Map Figure 2, Geologic Map Figure 3, Geologic Cross Section Figure 4, Wall/Column Footing Dimension Detail Figure 5, Typical Retaining Wall Drain Detail APPENDIX A FIELD INVESTIGATION Figures A-1 A-7, Logs of Exploratory Borings

4 TABLE OF CONTENTS (Concluded) APPENDIX B LABORATORY TESTING Table B-I, Summary of Laboratory Maximum Dry Density and Optimum Moisture Content Test Results Table B-II, Summary of Laboratory Expansion Index Test Results Table B-III, Summary of Laboratory Water-Soluble Sulfate Test Results Table B-IV, Summary of Laboratory Direct Shear Test Results APPENDIX C STORM WATER MANAGEMENT RECOMMENDATIONS APPENDIX D RECOMMENDED GRADING SPECIFICATIONS LIST OF REFERENCES

5 PRELIMINARY GEOTECHNICAL INVESTIGATION 1. PURPOSE AND SCOPE This report presents the results of our geotechnical investigation for the proposed renovation of Little Flower Haven located at 8585 La Mesa Boulevard in La Mesa, California (see Vicinity Map, Figure 1). The purpose of this geotechnical investigation is to evaluate the surface and subsurface soil conditions, general site geology, and to identify geotechnical constraints that may impact the planned improvements to the property. In addition, this report provides 2016 CBC seismic design criteria and recommendations for: grading, foundation design; concrete slab-on-grade and flatwork; retaining wall, lateral loading; storm water infiltration; and a discussion regarding the local geologic hazards including faulting and seismic shaking. This report is limited to the area shown on the Geologic Map, Figure 2. The scope of this investigation included: a review of readily available published and unpublished geologic literature (see List of References); drilling seven exploratory borings to a maximum depth of about 13 feet below ground surface; performing five, borehole infiltration tests using a Soil Moisture Corp Aardvark Permeameter; soil sampling; laboratory testing; engineering analyses; and preparation of this report. Appendix A presents the exploratory boring logs and details of the field investigation. Appendix B presents details of the laboratory tests and a summary of the test results. Appendix C present field data from the infiltration testing 2. SITE AND PROJECT DESCRIPTION The approximately 4.25-acre site is located at 8585 La Mesa Boulevard, La Mesa, California (See Site Vicinity Map, Figure 1). The site is bound on the north by La Mesa Boulevard; on the south, east, and west by single- and multi-family residential structures. The site is currently occupied by the former Little Flower Haven, an assisted living facility comprised of one large two- and three-story main building and some smaller single-story buildings, concrete walkways and hardscape areas, and numerous landscaped areas. There are also several existing underground utilities that cross the property. We understand that the project will consist of renovations and demolition of existing structures, to construct 7 new buildings; parking lots, surface improvements; and storm-water infiltration basins. Based on the preliminary plan, the majority of cuts and fills will be 5 feet or less from existing grades. Some areas of fill between 5 and 10 feet are planned. Retaining walls at various locations are also planned. Project No. G November 17, 2016

6 The above locations, site descriptions, and proposed development is based on a site reconnaissance, review of published geologic literature, our field investigations, and discussions with you. If development plans differ from those described herein, Geocon Incorporated should be contacted for review of the plans and possible revisions to this report. 3. GENERAL GEOLOGY AND GEOLOGIC SETTING The San Diego area is located in the Coastal Plain sub-province of the Peninsular Ranges Physiographic Provence. In San Diego County, the coastal plain runs parallel to the coast flanking the Peninsular Range and is characterized by a broad wedge of Tertiary sedimentary deposits that thicken from east to west capped by Pleistocene and Quaternary marine terrace deposits. Kennedy and Tan (2008) has mapped the site vicinity as Tertiary-age Stadium Conglomerate and weathered, Cretaceous-age granitic rock. 4. SOIL AND GEOLOGIC CONDITIONS Based on our field investigation, the site is underlain by undocumented fill over the Stadium Conglomerate and/or weathered granitic rock. Figure 2, Geologic Map (map pocket), shows the mapped soil and geologic units. Figure 3 shows geologic cross sections. The boring logs, presented in Appendix A, provide a description of the soils encountered during our field investigation. The geologic units are described below. 4.1 Undocumented Fill (Qudf) Approximately 3 to 13 feet of undocumented fill was encountered at the boring locations. Undocumented fill was also encountered in infiltration test P-5. Other areas unmapped of undocumented fill may exist throughout the site. Two of our borings encountered refusal and did not extend to the bottom of the undocumented fill. The undocumented fill consisted of: loose, dry to saturated; clayey, fine- to medium-grained sand. The undocumented fill is not suitable for the support of settlement-sensitive structures or improvements. In areas of new improvements, we recommend the undocumented fill be removed and replaced with compacted fill. 4.2 Stadium Conglomerate (Tst) Tertiary-age Stadium Conglomerate was observed in several borings. These deposits observed consisted of very dense, moist, yellowish brown, clayey, fine to medium sand with varying amounts of gravel and cobble. The Stadium Conglomerate deposits are suitable for the support of settlementsensitive structures or improvements. Project No. G November 17, 2016

7 4.3 Weathered Granitic Rock (Kgr) Cretaceous-age granitic rock was observed in Borings B-3 and B-7 underlying the undocumented fill. A rock outcrop was observed in the southeast corner of the property. The granitic rock consisted of very dense, brown, silty, fine- to coarse-grained sand. Refusal to the drill rig was encountered at both boring locations. Excavations that extend below the weathered zone will encounter difficult excavation and potentially generate oversize rock that will require special handling. The granitic rock is suitable for support of the planned improvements. 5. GROUNDWATER We did not encounter groundwater in any borings during the site investigation. We do not expect groundwater or seepage to be encountered during construction of the proposed project; however, it is not uncommon for seepage conditions to exist within the near surface elevations or develop where none previously existed especially at geologic contacts. Seepage is dependent on seasonal precipitation, irrigation, land use, among other factors, and varies as a result. Proper surface drainage will be important to future performance of the project. 6. GEOLOGIC HAZARDS 6.1 Faulting and Seismicity Review of the referenced geologic materials and our knowledge of the general area indicate that the site is not underlain by active, potentially active, or inactive faulting. 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 State of California Earthquake Fault Zone. We used EZ-FRISK (2015) to locate six known active faults are located within a search radius of 50 miles from the property. The 2008 USGS fault database, which provides several models and combinations of fault data, was used to evaluate the fault information. Based on this database, the Newport-Inglewood/Rose Canyon Fault Zone, located approximately 10 miles from the site, is the nearest known active fault and is the dominant source of potential ground motion. Earthquakes that might occur on the Newport-Inglewood/Rose Canyon Fault Zone or other faults within the southern California and northern Baja California area are potential generators of significant ground motion at the site. The estimated maximum earthquake magnitude and peak ground acceleration for the Newport- Inglewood/Rose Canyon Fault are 7.5 and 0.28g, respectively. The Table lists the estimated maximum earthquake magnitude and peak ground acceleration for the most dominant faults in relation to the site location. We calculated peak ground acceleration (PGA) using Boore-Atkinson (2008), Campbell-Bozorgnia (2008), and Chiou-Youngs (2008) acceleration-attenuation relationships. Project No. G November 17, 2016

8 TABLE DETERMINISTIC SPECTRA SITE PARAMETERS Fault Name Distance from Site (miles) Maximum Earthquake Magnitude (Mw) Boore- Atkinson 2008 (g) Peak Ground Acceleration Campbell- Bozorgnia 2008 (g) Chiou- Youngs 2008 (g) Newport-Inglewood/Rose Canyon Rose Canyon Coronado Bank Palos Verdes/Coronado Bank Elsinore Earthquake Valley In the event of a major earthquake on the referenced faults or other significant faults in the southern California and northern Baja California area, the site could be subjected to moderate to severe ground shaking. With respect to this hazard, the site is considered comparable to others in the general vicinity. We used EZ-FRISK to perform a probabilistic seismic hazard analysis. 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 estimated earthquake magnitude as a function of fault rupture length. 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 USGS, Campbell-Bozorgnia (2008) NGA USGS, and Chiou-Youngs (2007) NGA USGS 2008 in the analysis. Table presents the site-specific probabilistic seismic hazard parameters including acceleration-attenuation relationships and the probability of exceedance. Project No. G November 17, 2016

9 Probability of Exceedance TABLE PROBABILISTIC SEISMIC HAZARD PARAMETERS Boore-Atkinson, 2008 (g) Peak Ground Acceleration Campbell-Bozorgnia, 2008 (g) Chiou-Youngs, 2007 (g) 2% in a 50 Year Period % in a 50 Year Period % in a 50 Year Period 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 La Mesa. 6.2 Ground Rupture Based on our review of USGS (2016) there are no active, potentially active, or inactive faults crossing the subject site; therefore, the risk associated with earthquake ground rupture hazard is low. 6.3 Seiches and Tsunamis The site is located at an approximate elevation of 550 feet above mean sea level (MSL) and is not located downstream from any large body of water; therefore, the risk associated with flooding hazard due to tsunami or seiche events is low. 6.4 Liquefaction The risk of liquefaction or seismically induced settlement hazard at the site soil is low due to the lack of permanent, near-surface ground water and the dense nature and age of the underlying deposits. 6.5 Landslides The risk associated with landslide hazard is low due to the relatively flat topography of the site and vicinity. Project No. G November 17, 2016

10 7. CONCLUSIONS AND RECOMMENDATIONS 7.1 General From a geotechnical engineering standpoint, it is our opinion that the site is suitable for development of the proposed project provided the recommendations presented herein are implemented in design and construction of the project With the exception of possible moderate to strong seismic shaking, no other significant geologic hazards were observed or are known to exist on the site that would adversely affect the proposed project Our field investigation indicates the site is generally underlain by undocumented fill overlying Stadium Conglomerate and granitic rock Surficial soils (undocumented fill, topsoil, etc.) are not suitable for the support of settlesensitive structures or engineered fill and should be removed and replaced as compacted fill The on-site soils are suitable for use as compacted fill provided they are free of deleterious material We did not encounter groundwater or seepage during our field investigation. We do not expect groundwater or seepage to be encountered during construction of the proposed development; however, soil moisture conditions can vary depending on seasonal rainfall, irrigation, and drainage Subsurface conditions observed may be extrapolated to reflect general soil/geologic conditions at the site; however, some variations in subsurface conditions between boring locations should be expected. 7.2 Excavation and Soil Conditions Excavation of the undocumented fill should be possible with moderate to heavy effort using conventional, heavy-duty equipment. Excavation of the Stadium Conglomerate and weathered granitic rock may require a very heavy effort to excavated. Excavations into the granitic rock below the upper weathered zone may require specialized excavation techniques and could generate oversize rock. Oversized rock will require special handling and possibly exporting. Project No. G November 17, 2016

11 7.2.2 The soil encountered in the field investigation is considered to be both non-expansive (expansion index [EI] of 20 or less) and expansive (EI greater than 20) as defined by 2016 California Building Code (CBC) Section Table 7.2 presents soil classifications based on the expansion index. Based on the results of our laboratory testing, presented in Appendix B, and observations during drilling operations, we expect the majority of the onsite materials will possess a very low to low Expansion Index. TABLE 7.2 EXPANSION CLASSIFICATION BASED ON EXPANSION INDEX Expansion Index (EI) Expansion Classification 2013 CBC Expansion Classification 0 20 Very Low Non-Expansive Low Medium High Expansive Greater Than 130 Very High We performed laboratory tests on samples of the site materials to evaluate the percentage of water-soluble sulfate content. Appendix B presents the results from the laboratory watersoluble sulfate content tests. The test results indicate that on-site materials at the locations tested possess Exposure Class S0 sulfate exposure to concrete structures, as defined by 2016 CBC Section 1904 and ACI 318. 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 and other soil nutrients) may affect the concentration. We should perform additional laboratory tests to evaluate the soil at existing grade subsequent to the grading operations 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. 7.3 Grading Grading should be performed in accordance with the Grading Ordinance of the City of La Mesa and the Recommended Grading Specifications contained in Appendix D. The recommendations presented in this section take precedence over those presented in Appendix D. Project No. G November 17, 2016

12 7.3.2 Prior to commencing grading, a pre-construction conference should be held at the site with the project architect, grading contractor, civil engineer, geotechnical engineer, and inspection officials in attendance. Special soil handling requirements can be discussed at that time Site preparation should begin with the removal of all deleterious material and vegetation. The depth of removal should be such that material exposed in cut areas or soils to be used as fill are relatively free of organic matter. Material generated during stripping and/or site demolition should be exported from the site All existing utilities that will be abandoned should be completely removed, capped at the property limits, and the resulting excavation backfilled with compacted fill All compressible soil deposits, including undocumented fill and topsoil within planned new structural improvement areas (building pads, retaining walls, pavement, concrete hardscape, etc.) should be completely removed to the underlying Stadium Conglomerate or granitic rock and replaced as properly compacted fill. On site soil, which is free of deleterious material, is suitable for use as compacted fill. Where practical, the removals should extend a horizontal distanced beyond the edge of the structural improvement a distance of at least 5 feet, or the depth of the remedial removal, whichever is greater The surface of areas to receive fill should be scarified to a depth of approximately 8 inches; moisture conditioned to above optimum moisture content or as directed by the geotechnical engineer; and compacted. Fill soils may then be placed and compacted in layers to the design finish grade elevations. The layers should be no thicker than will allow for adequate bonding and compaction. All fill and backfill should be compacted to at least 90 percent of maximum dry density at or slightly above optimum moisture content, as determined by the current version of ASTM D To reduce the potential for differential settlement, it is recommended that the cut portion of cut/fill transition building pads be undercut at least 3 feet and replaced with properly compacted very low to low expansive fill soils. The base of undercuts should be sloped towards the front of the building pad or deeper fill area It is recommended that excavations be observed during grading by a representative of Geocon Incorporated to verify that soil and geologic conditions do not differ significantly from those anticipated. Project No. G November 17, 2016

13 7.3.9 It is the responsibility of the contractor to ensure that all excavations and trenches are properly shored and maintained in accordance with applicable OSHA rules and regulations in order to maintain safety and maintain the stability of adjacent existing improvements Import materials (if required), should consist of very low to low expansive (Expansion Index of 50 or less) soils. Prior to importing the material, samples from proposed borrow areas should be obtained and subjected to laboratory testing to determine whether the material conforms to the recommended criteria. At least 3 working days should be allowed for laboratory testing of the soil prior to its importation. Import materials should be free of oversize rock and construction debris. 7.4 Seismic Design Criteria We used the computer program U.S. Seismic Design Maps, provided by the USGS. Table 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 seconds. The values presented in Table are for the risktargeted maximum considered earthquake (MCE R). The site is considered Site Class D. We evaluated the Site Class based on the discussion in Section of the 2016 CBC and Table of ASCE TABLE CBC SEISMIC DESIGN PARAMETERS Parameter Value 2016 CBC Reference Site Class D Section Spectral Response Class B (short), S S g Figure (1) Spectral Response Class B (1 sec), S g Figure (2) Site Coefficient, F a Table (1) Site Coefficient, F v Table (2) Maximum Considered Earthquake Spectral Response Acceleration (short), S MS g Section (Eqn 16-37) Maximum Considered Earthquake Spectral Response Acceleration (1 sec), S M g Section (Eqn 16-38) 5% Damped Design Spectral Response Acceleration (short), S DS g Section (Eqn 16-39) 5% Damped Design Spectral Response Acceleration (1 sec), S D g Section (Eqn 16-40) Project No. G November 17, 2016

14 7.4.2 Table 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 (MCE G). TABLE CBC SITE ACCELERATION PARAMETERS Parameter Value ASCE 7-10 Reference Site Class D -- Mapped MCE G Peak Ground Acceleration, PGA g Figure 22-7 Site Coefficient, F PGA Table Site Class Modified MCE G Peak Ground Acceleration, PGA M g Section (Eqn ) Conformance to the criteria for seismic design does not constitute any guarantee or assurance that significant structural damage or ground failure will not occur in the event of a maximum level earthquake. The primary goal of seismic design is to protect life and not to avoid all damage, since such design may be economically prohibitive. 7.5 Conventional Shallow Foundations and Slabs-On-Grade The foundation and slab-on-grade recommendations presented herein are based on soil conditions only and are not intended to be used in lieu of those required for structural purposes The following foundation recommendations are based on the assumption that remedial grading will be performed as recommended herein and that footings will be founded entirely on properly compacted fill. These recommendations also assume that the soils within 3 feet of finish grade will consist of soils with an Expansion Index of 50 or less Conventional continuous footings should have a minimum embedment depth of 18 inches below lowest adjacent grade. The footings should be at least 12 inches wide. Isolated spread footings should be at least 2 feet square and founded at least 18 inches below lowest adjacent pad grade. A footing dimension detail is presented on Figure Footings, as proportioned above, may be designed for an allowable soil bearing pressure of 2,500 pounds per square foot (psf), dead plus live loads. The soil bearing pressure may be Project No. G November 17, 2016

15 increased by 300 psf and 500 psf for each additional foot of foundation width and depth, respectively, up to a maximum allowable soil bearing pressure of 4,000 psf We estimate total static settlement as a result of footings imposing the above bearing pressures to be on the order of 1-inch total and ¾-inch differential in 40 feet The allowable bearing pressure may be increased by up to one-third for transient loads due to wind or seismic forces Continuous footings should be reinforced with four, No. 5 steel, reinforcing bars, two placed near the top of the footing and two near the bottom. The project structural engineer should design reinforcement for spread footings Foundation excavations should be observed by the geotechnical engineer (a representative of Geocon Incorporated) prior to the placement of reinforcing steel and concrete to assess that the exposed soil conditions are consistent with those expected and that they have been extended to the appropriate bearing strata. If unexpected soil conditions are encountered, foundation modifications may be required The contractor should maintain the subgrade soils at the soil placement moisture content by sprinkling water in the footing excavations and slab area as necessary Interior concrete slabs-on-grade for the proposed structure should be at least 5 inches thick. Minimum slab reinforcement should consist of No. 3 steel, reinforcing bars placed 18 inches on center in both horizontal directions and positioned near the slab midpoint A vapor retarder should underlie slabs that may receive moisture-sensitive floor coverings or may be used to store moisture-sensitive materials. The vapor retarder design should be consistent with the guidelines presented in the American Concrete Institute s (ACI) Guide for Concrete Slabs that Receive Moisture-Sensitive Flooring Materials (ACI 302.2R-06). The vapor retarder should be installed in accordance with manufacturer s recommendations and ASTM requirements in a manner that prevents puncture. The project architect or developer should specify the type of vapor retarder used based on the type of floor covering that will be installed and if the structure will possess a humidity controlled environment The project foundation engineer, architect, and/or developer should determine the thickness of the bedding sand below the slab. Geocon Incorporated should be contacted to provide recommendations if the bedding sand is thicker than 6 inches. Project No. G November 17, 2016

16 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. The foundation design engineer should designate 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 Crack control joints should be spaced at intervals not greater than 10 feet and should be constructed using sawcuts or other methods as soon as practical following concrete placement. Crack control joints should extend a minimum depth of one-fourth the slab thickness. Construction joints should be designed by the project structural engineer Exterior slab recommendations assume soils within 3 feet of finish grade consist of low expansive soils (EI less than 50). Exterior slabs not subject to vehicle loads should be at least 4 inches thick and reinforced with No. 3 steel reinforcing bars spaced 24 inches or 6x6- W2.9/W2.9 (6x6-6/6) welded wire mesh. The mesh should be placed within the upper onethird of the slab. Proper mesh positioning is critical to future performance of the slabs. The contractor should take extra measures to provide proper mesh placement. Prior to construction of slabs, the subgrade should be moisture conditioned to at least optimum moisture content and compacted to a dry density of at least 90 percent of the laboratory maximum dry density The recommendations presented herein are intended to reduce the potential for cracking of slabs and foundations as a result of differential movement. However, even with the incorporation of the recommendations presented herein, foundations and slabs-on-grade will still crack. The occurrence of concrete shrinkage cracks is independent of the soil supporting characteristics. Their occurrence may be reduced and/or controlled by: limiting the slump of the concrete; the use of crack control joints; and proper concrete placement and curing. Literature provided by the Portland Concrete Association (PCA) and American Concrete Institute (ACI) present recommendations for proper concrete mix, construction, and curing practices, and should be incorporated into project construction. 7.6 Retaining Walls Retaining walls 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 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 pcf. Where the backfill will be inclined at 2:1 (horizontal:vertical), an active soil pressure of 50 pcf is recommended. These active pressures assume low expansive soil Project No. G November 17, 2016

17 (Expansion Index less than 50) will be used as retaining wall backfill. Clayey soil should not be used as retaining wall backfill Where walls are restrained from movement at the top, an additional uniform pressure of 8H psf should be added to the active soil pressure where the walls are less than 8 feet tall. Walls in excess of 8 feet should be designed to accommodate an additional uniform pressure of 12H for restrained conditions 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 Soil to be used as backfill should be stockpiled and samples obtained for laboratory testing to evaluate its suitability for use as wall backfill. Modified lateral earth pressures will be required if backfill soils do not meet the required expansion index. City or regional standard wall designs, if used, are based on a specific active lateral earth pressure and/or soil friction angle. On-site soils might not meet the design values used for City or regional standard wall design. Geocon Incorporated should be consulted if City or regional standard wall designs will be used to assess the suitability of on-site soil for use as wall backfill Unrestrained walls will move laterally when backfilled 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 wall designer should provide appropriate lateral deflection quantities for planned retaining walls structures, if applicable. These lateral values should be considered when planning types of improvements above retaining wall structures Retaining walls should be provided with a drainage system adequate to prevent the buildup of hydrostatic forces and should be waterproofed as required by the project architect. The use of drainage openings through the base of the wall (weep holes) is not recommended where the seepage could be a nuisance or otherwise adversely affect the property adjacent to the base of the wall. The above recommendations assume a properly compacted granular (EI <50) free-draining backfill material with no hydrostatic forces or imposed surcharge load. A typical retaining wall drain detail is shown on Figure 5. If conditions different than those described are expected, or if specific drainage details are desired, Geocon Incorporated should be contacted for additional recommendations In general, wall foundations having a minimum depth and width of one foot may be designed for an allowable soil bearing pressure of 2,500 psf, provided the soil within 3 feet below the base of the wall consists of compacted fill with an Expansion Index of less than 50. The soil bearing pressure may be increased by 300 psf and 500 psf for each additional foot of Project No. G November 17, 2016

18 foundation width and depth, respectively, up to a maximum allowable soil bearing pressure of 4,000 psf. The proximity of the foundation to the top of a slope steeper than 3:1 could impact the allowable soil bearing pressure. Therefore, Geocon Incorporated should be consulted where such a condition is expected The structural engineer should determine the seismic design category for the project. If the project possesses a seismic design category of D, E, or F, the proposed retaining walls should be designed with seismic lateral pressure. A seismic load of 19H should be used for design on walls that support more than 6 feet of backfill in accordance with Section 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. We used the peak site acceleration, PGA M, of 0.39g calculated from ASCE 7-10 Section and applied a pseudo-static coefficient of For resistance to lateral loads, a passive earth pressure equivalent to a fluid density of 300 pounds per cubic foot (pcf) is recommended for footings or shear keys poured neat against properly compacted granular fill soils or undisturbed natural soils. The passive pressure assumes a horizontal surface extending away from the base of the wall at least five feet or three times the surface generating the passive pressure, whichever is greater. The upper 12 inches of material not protected by floor slabs or pavement should not be included in the design for lateral resistance A friction coefficient of 0.40 may be used for resistance to sliding between soil and concrete. This friction coefficient may be combined with the passive earth pressure when determining resistance to lateral loads The recommendations presented above are generally applicable to the design of rigid concrete or masonry retaining walls having a maximum height of eight feet. In the event that walls higher than eight feet or other types of walls (such as crib or mechanically stabilized earth-type walls) are planned, Geocon Incorporated should be consulted for additional recommendations. 7.7 Storm Water Management If storm water management devices are not properly designed and constructed, there is a risk for distress to improvements and properties located hydrologically down gradient or adjacent to these devices. Factors such as the amount of water being detained, its residence time, and soil permeability have an important effect on seepage transmission and the potential adverse impacts that may occur if the storm water management features are not properly designed Project No. G November 17, 2016

19 and constructed. We have not performed a hydrogeological study at the site. If infiltration of storm water runoff into the subsurface occurs, downstream improvements may be subjected to seeps, springs, slope instability, raised groundwater, movement of foundations and slabs, or other undesirable impacts as a result of water infiltration A summary of our study and storm water management recommendations are provided in Appendix C. 7.8 Site Drainage and Moisture Protection 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 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 structure In the case of basement walls or building walls retaining landscaping areas, a water-proofing system should be used on the wall and joints, and a Miradrain drainage panel (or similar) should be placed over the waterproofing. The project architect or civil engineer should provide detailed specifications on the plans for all waterproofing and drainage 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 Landscaping planters adjacent to paved areas are not recommended due to the potential for surface or irrigation water to infiltrate the pavement's subgrade and base course. Area drains to collect excess irrigation water and transmit it to drainage structures or impervious abovegrade planter boxes can be used. In addition, where landscaping is planned adjacent to the pavement, construction of a cutoff wall along the edge of the pavement that extends at least 6 inches below the bottom of the base material should be considered. 7.9 Slope Maintenance Slopes that are steeper than 3:1 (horizontal:vertical) may, under conditions that are both difficult to prevent and predict, be susceptible to near-surface (surficial) slope instability. The instability is typically limited to the outer 3 feet of a portion of the slope and usually does not directly impact the improvements on the pad areas above or below the slope. The Project No. G November 17, 2016

20 occurrence of surficial instability is more prevalent on fill slopes and is generally preceded by a period of heavy rainfall, excessive irrigation, or the migration of subsurface seepage. The disturbance and/or loosening of the surficial soils, as might result from root growth, soil expansion, or excavation for irrigation lines and slope planting, may also be a significant contributing factor to surficial instability. It is therefore recommended that, to the maximum extent practical: (a) disturbed/loosened surficial soils be either removed or properly recompacted, (b) irrigation systems be periodically inspected and maintained to eliminate leaks and excessive irrigation, and (c) surface drains on and adjacent to slopes be periodically maintained to preclude ponding or erosion. Although the incorporation of the above recommendations should reduce the potential for surficial slope instability, it will not eliminate the possibility and, therefore, it may be necessary to rebuild or repair a portion of the project's slopes in the future Grading and Foundation Plan Review The geotechnical engineer and engineering geologist should review the grading and foundation plans prior to final submittal to check their compliance with the recommendations of this report and to determine the need for additional comments, recommendations and/or analysis. Project No. G November 17, 2016

21 LIMITATIONS AND UNIFORMITY OF CONDITIONS 1. 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. 2. 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. 3. 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. 4. 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. G November 17, 2016

22

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27 APPENDIX A

28 APPENDIX A FIELD INVESTIGATION The field investigation was conducted on November 1, 2016, and consisted of a site reconnaissance and drilling seven, shallow exploratory borings using an Ingersol Rand A-300, truck-mounted, drill rig equipped with 8-inch-diameter augers at the approximate location should on Figure 2. Relatively undisturbed and bulk soil samples were collected from the borings. The soil conditions encountered in the borings were visually examined, classified, and logged in general accordance with American Society for Testing and Materials (ASTM) practice for Description and Identification of Soils (Visual-Manual Procedure D 2488). Logs of the borings are presented on Figures A-1 through A-7. The logs depict the soil and geologic conditions encountered and the depth at which samples were obtained. Infiltration testing was performed at ten locations shown on Figure 2. The infiltration testing was conducted in the 8-inch-diameter borings at depths of approximately 3.5 to 5 feet below ground surface using a SoilMoisture Corp Aardvark Permeameter. Project No. G November 17, 2016

29 PROJECT NO. G DEPTH IN FEET SAMPLE LITHOLOGY GROUNDWATER SOIL CLASS BORING B 1 NO. ELEV. (MSL.) 553' DATE COMPLETED (USCS) EQUIPMENT IR A-300 BY: B. KUNA PENETRATION RESISTANCE (BLOWS/FT.) DRY DENSITY (P.C.F.) MOISTURE CONTENT (%) 0 B1-1 SM MATERIAL DESCRIPTION FILL Dense, damp, brown, Silty, SAND with gravel 2 B1-2 30/36" /13" 6 SC Loose, moist, brown, Clayey, fine to coarse SAND with gravel 8 B1-3 4/4" B1-4 CL Dense, wet, gray, Clayey SAND with gravel 7/20" B1-5 CL Loose, wet, gray, Clayey SAND with gravel REFUSAL AT 13 FEET No groundwater encountered Backfilled with cuttings mixed with bentonite chips Figure A-1, Log of Boring B 1, Page 1 of 1 G GPJ SAMPLE SYMBOLS... SAMPLING UNSUCCESSFUL... DISTURBED OR BAG SAMPLE... STANDARD PENETRATION TEST... CHUNK SAMPLE... DRIVE SAMPLE (UNDISTURBED)... WATER TABLE OR SEEPAGE NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES. GEOCON

30 PROJECT NO. G DEPTH IN FEET SAMPLE LITHOLOGY GROUNDWATER SOIL CLASS BORING B 2 NO. ELEV. (MSL.) 558' DATE COMPLETED (USCS) EQUIPMENT IR A-300 BY: B. KUNA PENETRATION RESISTANCE (BLOWS/FT.) DRY DENSITY (P.C.F.) MOISTURE CONTENT (%) 0 B2-1 SC MATERIAL DESCRIPTION FILL Dense, damp, brown, Clayey, fine to course SAND with gravel 2 4 B2-2 SC STADIUM CONGLOMERATE Dense, wet, mottled grayish-brown and light brown, fine to medium Clayey SAND with gravel 16/30" B2-3 18/50" B2-4 50/3" 10 B2-5 SC Very dense, moist, yellowish-brown, Clayey, fine to medium SAND with silt and gravel 50/6" REFUSAL AT 11.5 FEET No groundwater encountered Backfilled with cuttings Figure A-2, Log of Boring B 2, Page 1 of 1 G GPJ SAMPLE SYMBOLS... SAMPLING UNSUCCESSFUL... DISTURBED OR BAG SAMPLE... STANDARD PENETRATION TEST... CHUNK SAMPLE... DRIVE SAMPLE (UNDISTURBED)... WATER TABLE OR SEEPAGE NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES. GEOCON

31 PROJECT NO. G DEPTH IN FEET SAMPLE LITHOLOGY GROUNDWATER SOIL CLASS BORING B 3 NO. ELEV. (MSL.) 565' DATE COMPLETED (USCS) EQUIPMENT IR A-300 BY: B. KUNA PENETRATION RESISTANCE (BLOWS/FT.) DRY DENSITY (P.C.F.) MOISTURE CONTENT (%) 0 B3-1 SC 3.5-INCHES CONCRETE MATERIAL DESCRIPTION FILL Very dense, damp, brown, Clayey, fine to coarse SAND with gravel 2 50/5" 4 B3-2 50/4.5" 6 SM WEATHERED GRANITIC ROCK Very dense, moist, light brown to brown, Silty, fine to coarse SAND 8 B3-3 50/6.5" /3" REFUSAL AT 11 FEET Backfilled with cuttings No groundwater encountered Figure A-3, Log of Boring B 3, Page 1 of 1 G GPJ SAMPLE SYMBOLS... SAMPLING UNSUCCESSFUL... DISTURBED OR BAG SAMPLE... STANDARD PENETRATION TEST... CHUNK SAMPLE... DRIVE SAMPLE (UNDISTURBED)... WATER TABLE OR SEEPAGE NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES. GEOCON

32 PROJECT NO. G DEPTH IN FEET SAMPLE LITHOLOGY GROUNDWATER SOIL CLASS BORING B 4 NO. ELEV. (MSL.) 560' DATE COMPLETED (USCS) EQUIPMENT IR A-300 BY: B. KUNA PENETRATION RESISTANCE (BLOWS/FT.) DRY DENSITY (P.C.F.) MOISTURE CONTENT (%) 0 B4-1 SM MATERIAL DESCRIPTION FILL Very dense, damp, brown, Silty SAND with gravel 2 4 SM STADIUM CONGLOMERATE Very dense, moist, brown, Silty, fine to medium SAND with gravel B4-2 50/3" B4-3 SC Very dense, moist, brown, gravelly, fine to coarse SAND with clay 50/4" B4-4 50/5" 12 REFUSAL AT 12 FEET No groundwater encountered Backfilled with cuttings Figure A-4, Log of Boring B 4, Page 1 of 1 G GPJ SAMPLE SYMBOLS... SAMPLING UNSUCCESSFUL... DISTURBED OR BAG SAMPLE... STANDARD PENETRATION TEST... CHUNK SAMPLE... DRIVE SAMPLE (UNDISTURBED)... WATER TABLE OR SEEPAGE NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES. GEOCON

33 PROJECT NO. G DEPTH IN FEET SAMPLE LITHOLOGY GROUNDWATER SOIL CLASS BORING B 5 NO. ELEV. (MSL.) 557' DATE COMPLETED (USCS) EQUIPMENT IR A-300 BY: B. KUNA PENETRATION RESISTANCE (BLOWS/FT.) DRY DENSITY (P.C.F.) MOISTURE CONTENT (%) 0 B5-1 SM MATERIAL DESCRIPTION FILL Very dense, damp, brown, Clayey SAND with gravel 2 4 SM STADIUM CONGLOMERATE Very dense, damp, brown, Silty, fine to coarse SAND with gravel B5-2 50/4.5" 6 REFUSAL AT 7.5 FEET No groundwater encountered Backfill with cuttings Figure A-5, Log of Boring B 5, Page 1 of 1 G GPJ SAMPLE SYMBOLS... SAMPLING UNSUCCESSFUL... DISTURBED OR BAG SAMPLE... STANDARD PENETRATION TEST... CHUNK SAMPLE... DRIVE SAMPLE (UNDISTURBED)... WATER TABLE OR SEEPAGE NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES. GEOCON

34 PROJECT NO. G DEPTH IN FEET SAMPLE LITHOLOGY GROUNDWATER SOIL CLASS BORING B 6 NO. ELEV. (MSL.) 557' DATE COMPLETED (USCS) EQUIPMENT IR A-300 BY: B. KUNA PENETRATION RESISTANCE (BLOWS/FT.) DRY DENSITY (P.C.F.) MOISTURE CONTENT (%) 0 B6-1 SC MATERIAL DESCRIPTION FILL Hard, moist, brown, fine to medium Clayey SAND with gravel 2 B6-2 50/6" 4 6 REFUSAL AT 7.5 FEET No groundwater encountered Backfilled with cuttings Figure A-6, Log of Boring B 6, Page 1 of 1 G GPJ SAMPLE SYMBOLS... SAMPLING UNSUCCESSFUL... DISTURBED OR BAG SAMPLE... STANDARD PENETRATION TEST... CHUNK SAMPLE... DRIVE SAMPLE (UNDISTURBED)... WATER TABLE OR SEEPAGE NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES. GEOCON

35 PROJECT NO. G DEPTH IN FEET SAMPLE LITHOLOGY GROUNDWATER SOIL CLASS BORING B 7 NO. ELEV. (MSL.) 564' DATE COMPLETED (USCS) EQUIPMENT IR A-300 BY: B. KUNA PENETRATION RESISTANCE (BLOWS/FT.) DRY DENSITY (P.C.F.) MOISTURE CONTENT (%) 0 B7-1 SC MATERIAL DESCRIPTION FILL Medium dense, damp, dark reddish-brown, Clayey, fine to coarse SAND 2 B7-2 14/12" SM WEATHERED GRANITIC ROCK Very dense, moist, olive-brown, Silty, fine to coarse SAND B7-3 50/5" 6 REFUSAL AT 7.5 FEET No groundwater encountered Backfilled with cuttings Figure A-7, Log of Boring B 7, Page 1 of 1 G GPJ SAMPLE SYMBOLS... SAMPLING UNSUCCESSFUL... DISTURBED OR BAG SAMPLE... STANDARD PENETRATION TEST... CHUNK SAMPLE... DRIVE SAMPLE (UNDISTURBED)... WATER TABLE OR SEEPAGE NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES. GEOCON

36 APPENDIX B

37 APPENDIX B LABORATORY TESTING We performed laboratory tests in accordance with the current, generally accepted test methods of the American Society for Testing and Materials (ASTM) or other suggested procedures. We tested selected samples for maximum dry density and optimum moisture content, expansion index, water-soluble sulfate exposure, and direct shear. The results of our laboratory tests are presented on Tables B-I through B-IV. TABLE B-I SUMMARY OF LABORATORY MAXIMUM DRY DENSITY AND OPTIMUM MOISTURE CONTENT TEST RESULTS ASTM D 1557 Sample No. Description Maximum Dry Density (pcf) Optimum Moisture Content (% dry wt.) B1-1 Brown, silty, fine to coarse SAND B5-1 Red-brown, silty, fine to coarse SAND B7-1 Brown, clayey, fine to coarse SAND TABLE B-II SUMMARY OF LABORATORY EXPANSION INDEX TEST RESULTS ASTM D 4829 Sample No. Moisture Content (%) Before Test After Test Dry Density (pcf) Expansion Index Expansion Classification B Low B Very low B Low TABLE B-III SUMMARY OF LABORATORY WATER-SOLUBLE SULFATE TEST RESULTS CALIFORNIA TEST NO. 417 Sample No. Water-Soluble Sulfate (%) Classification B Not Applicable, S0 B Not Applicable, S0 B Not Applicable, S0 Project No. G B-1 - November 17, 2016

38 Sample No. TABLE B-IV SUMMARY OF LABORATORY DIRECT SHEAR TEST RESULTS ASTM D 3080 Dry Density (pcf) Moisture Content (%) Initial Final Unit Cohesion (psf) Angle of Shear Resistance (degrees) B Project No. G B-2 - November 17, 2016

39 APPENDIX C

40 APPENDIX C STORM WATER MANAGEMENT If storm water management devices are not properly designed and constructed, there is a risk for distress to improvements and properties located hydrologically down gradient or adjacent to these devices. Factors such as the amount of water being detained, its residence time, and soil permeability have an important effect on seepage transmission and the potential adverse impacts that may occur if the storm water management features are not properly designed and constructed. We have not performed a hydrogeological study at the site. If infiltration of storm water runoff into the subsurface occurs, downstream improvements may be subjected to seeps, springs, slope instability, raised groundwater, movement of foundations and slabs, or other undesirable impacts as a result of water infiltration. Hydrologic Soil Group The United States Department of Agriculture (USDA), Natural Resources Conservation Services, provides general information regarding soil conditions for areas within the United States. The USDA website also provides the Hydrologic Soil Group. Table C-1 presents the descriptions of the hydrologic soil groups. TABLE C-1 HYDROLOGIC SOIL GROUP DEFINITIONS Soil Group A B C D Soil Group Definition Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. The subject property is underlain by: undocumented fill, Stadium Conglomerate, and granitic rock. The subject site falls within Hydraulic Soil Group D, which has a very slow infiltration rating. Table C-2 presents the information from the USDA website for the property. - C-1 -

41 TABLE C-2 USDA WEB SOIL SURVEY HYDROLOGIC SOIL GROUP Map Unit Name Map Unit Symbol Approximate Percentage of Property Hydrologic Soil Group ksat of Most Limiting Layer (inches/hour) Redding-Urban Land complex, 2 to 9 percent slopes RhC 100 D 0.00 to 0.06 In-Situ Testing We performed five, field-saturated hydraulic conductivity tests at depths of approximately 3.5 to 5 feet below the ground surface using a SoilMoisture Corp Aardvark Permeameter at the approximate locations shown on Figure 2. Tests were performed in 8-inch-diameter borings. Test P-5 caved in the undocumented fill, so the test hole was cleanout out and run in an approximately 10-inch-diameter hole. Table C-3 presents the results of the field-saturated hydraulic conductivity testing calculated using the USBR method. We used the guidelines presented in the Riverside County Low Impact Development BMP Design Handbook which references the United States Bureau of Reclamation Well Permeameter Test Method (USBR ). Based on this widely accepted guideline, the saturated hydraulic conductivity (Ksat) is equal to the infiltration rate. Therefore, the Ksat value determined from the Aardvark Permeameter test is the unfactored infiltration rate. The Ksat (infiltration rate) equation provided in the Riverside County Handbook was used to compute the unfactored infiltration rate. TABLE C-3 UNFACTORED, FIELD-SATURATED, INFILTRATION TEST RESULTS USING THE SOILMOISTURE CORP AARDVARK PERMEAMETER Location Depth (inches) Geologic Unit Field Saturated Hydraulic Conductivity, Kf (inches/hour) P-1 42 Qudf 0.2 P-2 42 Qudf/Tst P-3 57 Qudf/Tst 0.01 P-4 53 Qudf/Tst 0.04 P-5 57 Qudf 0.83 Soil permeability values from in-situ tests can vary significantly from one location to another due to the non-homogeneous characteristics inherent to most soil. However, if a sufficient amount of field and laboratory test data is obtained, a general trend of soil permeability can usually be evaluated. For this project and for storm water purposes, the test results presented herein should be considered approximate values. - C-2 -

42 STORM WATER MANAGEMENT CONCLUSIONS Soil Types Undocumented Fill (Qudf) Undocumented fill covers the majority of the site. The undocumented fill consists of loose, dry to saturated; clayey, fine- to medium-grained sand. Recommendations have been provided for complete removal and compaction of undocumented fill in areas of proposed structural improvements. Water that is allowed to migrate into the undocumented fill and/or compacted fill could cause settlement below structural improvements adjacent to proposed BMPs. Infiltration into fills located within structural improvement areas is not recommended Compacted Fill We expect compacted fill will exists throughout the majority of the property at the completion of grading. Water that is allowed to infiltrate into the compacted fill could cause saturation and settlement to proposed improvements founded on the compacted fill. Infiltration basins should be deepened through the fill to the native formational bedrock soil. Stadium Conglomerate Stadium Conglomerate underlies the compacted fill. The Stadium Conglomerate is a very dense cobble conglomerate in a silty to clayey sand matrix that typically exhibits very slow infiltration characteristics. This geologic unit has a potential for lateral water migration. Therefore, infiltration should not be allowed within the Stadium Conglomerate in areas adjacent to existing improvements and compacted fill. Infiltration Rates The results of the testing show infiltration rates ranging from approximately to 0.8 inches per hour. Infiltration tests P-1 and P-5 were in area of undocumented fill that was very loose. During remedial grading the undocumented fill will be removed and replaced as compacted fill, therefore, these rates should not be relied upon for final design for basins in these areas. The rates are not high enough to support full infiltration, however, provided precautions are taken to deepen basins through fill and into native formational bedrock, as well as the use of side liners and drains, partial infiltration is considered feasible. Existing Improvements and Proposed Foundations Existing structures surround the property. Additionally, proposed new building will be constructed. We do not recommend infiltrating into soils that support existing or proposed improvements. Therefore, basins should be set back a horizontal distance of at least 20 feet from existing and proposed new foundations. - C-3 -

43 Groundwater Groundwater was not encountered during our geotechnical investigation. We expect groundwater is at a depth greater than 50 feet below current grades. Groundwater is not a constraint for storm water infiltration. Existing and New Utilities Existing utilities are located in several areas on the property within existing streets and parking lots. Therefore, infiltration near these utilities is considered infeasible. We also expect new utilities will be constructed for the proposed building. Infiltration near proposed new utilities is not recommended. Soil or Groundwater Contamination We are unaware of contaminated soil or groundwater on the property. Therefore, infiltration associated with this risk is considered feasible. Storm Water Management Devices Side liners and subdrains are recommended in the design and construction of the planned storm water devices. Where basins are planned in areas of compacted fill, the basins should be deepened to at least 1 foot into the native formational bedrock. Basins located fill areas that are not extended to the native bedrock should be fully lined. The liners should be impermeable (e.g. High-density polyethylene, HDPE, with a thickness of about 30 mil or equivalent Polyvinyl Chloride, PVC) to prevent water migration. The subdrains should be perforated within the liner area, installed at the bottom of the basin, be at least 3 inches in diameter and consist of Schedule 40 PVC pipe. The subdrains outside of the liner should consist of solid pipe. The penetration of the liners at the subdrains should be properly waterproofed. The subdrains should be connected to a proper outlet. The devices should also be installed in accordance with the manufacturer s recommendations. Storm Water Standard Worksheets The SWS requests the geotechnical engineer complete the Categorization of Infiltration Feasibility Condition (Worksheet C.4-1 or I-8) worksheet information to help evaluate the potential for infiltration on the property. The attached Worksheet C.4-1 presents the completed information for the submittal process. The regional storm water standards also have a worksheet (Worksheet D.5-1 or Form I-9) that helps the project civil engineer estimate the factor of safety based on several factors. Table C-4 describes the suitability assessment input parameters related to the geotechnical engineering aspects for the factor of safety determination. - C-4 -

44 TABLE C-4 SUITABILITY ASSESSMENT RELATED CONSIDERATIONS FOR INFILTRATION FACILITY SAFETY FACTORS Consideration High Concern 3 Points Medium Concern 2 Points Low Concern 1 Point Assessment Methods Use of soil survey maps or simple texture analysis to estimate short-term infiltration rates. Use of well permeameter or borehole methods without accompanying continuous boring log. Relatively sparse testing with direct infiltration methods Use of well permeameter or borehole methods with accompanying continuous boring log. Direct measurement of infiltration area with localized infiltration measurement methods (e.g., infiltrometer). Moderate spatial resolution Direct measurement with localized (i.e. small-scale) infiltration testing methods at relatively high resolution or use of extensive test pit infiltration measurement methods. Predominant Soil Texture Silty and clayey soils with significant fines Loamy soils Granular to slightly loamy soils Site Soil Variability Highly variable soils indicated from site assessment or unknown variability Soil boring/test pits indicate moderately homogenous soils Soil boring/test pits indicate relatively homogenous soils Depth to Groundwater/ Impervious Layer <5 feet below facility bottom 5-15 feet below facility bottom >15 feet below facility bottom Table C-5 presents the estimated factor values for the evaluation of the factor of safety. The factor of safety is determined using the information contained in Table C-4 and the results of our geotechnical investigation. Table C-5 only presents the suitability assessment safety factor (Part A) of the worksheet. The project civil engineer should evaluate the safety factor for design (Part B of Worksheet D.5-1) and use the combined safety factor for the design infiltration rate. TABLE C-5 FACTOR OF SAFETY WORKSHEET D.5-1 DESIGN VALUES PART A 1 Suitability Assessment Factor Category Assigned Weight (w) Factor Value (v) Product (p = w x v) Assessment Methods Predominant Soil Texture Site Soil Variability Depth to Groundwater/Impervious Layer Suitability Assessment Safety Factor, S A = p The project civil engineer should complete Worksheet D.5-1 or Form I-9 to determine the overall factor of safety. - C-5 -

45 CONCLUSIONS Our results indicate the site has highly variable sub-surface conditions and relatively low infiltration characteristics. Because of these site conditions, it is our opinion that there is a high probability for lateral water migration. Considering the presence of undocumented fill and compacted fill that will exists at the completion of grading, it is our opinion that full and partial infiltration is infeasible unless precautions are taken to prevent impacts to existing and proposed foundations and utilities. The site is considered infeasible for full infiltration. The site is considered feasible for partial infiltration provided basins are deepened through the undocumented and compacted fill and into the native bedrock. In some areas this may not be feasible considering the depth of the fills. All basins should be set back at least 20 feet from existing and proposed new foundations and utilities. Additionally, basins should be deepened to a depth of at least 4 feet below the bottom of existing and proposed building foundations located within 50 feet of the basin area. All basins should include side liners and drains at the bottom of the basin. Our evaluation included the soil and geologic conditions, estimated settlement and volume change of the underlying soil, slope stability, utility considerations, groundwater mounding, retaining walls, foundations and existing groundwater elevations. If water is allowed to infiltrate into undocumented fill and compacted fill soils, or migrate below existing and proposed foundations, settlement and distress to foundations and improvements could occur. - C-6 -

46 Appendix C: Geotechnical and Groundwater Investigation Requirements Categorization of Infiltration Feasibility Condition Worksheet C.4-1 Part 1 - Full Infiltration Feasibility Screening Criteria Would infiltration of the full design volume be feasible from a physical perspective without any undesirable consequences that cannot be reasonably mitigated? Criteria Screening Question Yes No Is the estimated reliable infiltration rate below proposed facility locations greater than 0.5 inches per hour? The response 1 to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D. Provide basis: X We performed 5 infiltration tests. The results of the infiltration rates range from to 0.8 inches per hour. Using a factor of safety of 2.0 for feasibility determination, the factored infiltration rates are to 0.4 inches per hour. This shows the soil has very slow infiltration characteristics, and using a factor of safety of 2 for screening, the site does not have a reliable infiltration rate greater than 0.5 inches per hour. Full infiltration is considered infeasible. 2 Can infiltration greater than 0.5 inches per hour be allowed without increasing risk of geotechnical hazards (slope stability, groundwater mounding, utilities, or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2. X The site is underlain by undocumented fill, the Scripps Formation, and Granitic Rock. At the completion of grading, we expect the majority of the site will be underlain by compacted fill. The specific geologic or geotechnical hazard for this site is the potential for lateral migration of infiltration water to adjacent foundations, utilities, and behind retaining walls. The relatively slow infiltration test results is a reflection of the dense nature of the site bedrock soils. We expect that infiltration of storm water will be occluded and could potentially migrate laterally which could impact adjacent utilities and foundations. C-11

47 Appendix C: Geotechnical and Groundwater Investigation Requirements Worksheet C.4-1 Page 2 of 4 Criteria Screening Question Yes No 3 Can infiltration greater than 0.5 inches per hour be allowed without increasing risk of groundwater contamination (shallow water table, storm water pollutants or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. X Provide basis: Groundwater was not encountered and is expected to be at least 50 feet below existing ground surface. Therefore, in our opinion, infiltration will not increase the risk of groundwater contamination. Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability. 4 Can infiltration greater than 0.5 inches per hour be allowed without causing potential water balance issues such as change of seasonality of ephemeral streams or increased discharge of contaminated groundwater to surface waters? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. X Provide basis: Infiltration is not anticipated to have a negative impact on nearby water balance or discharge of contaminated groundwater to surface waters. Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability. Part 1 Result* If all answers to rows 1-4 are Yes a full infiltration design is potentially feasible. The feasibility screening category is Full Infiltration If any answer from row 1-4 is No, infiltration may be possible to some extent but would not generally be feasible or desirable to achieve a full infiltration design. Proceed to Part 2 *To be completed using gathered site information and best professional judgment considering the definition of MEP in the MS4 Permit. Additional testing and/or studies may be required by the City to substantiate findings. No C-12

48 Appendix C: Geotechnical and Groundwater Investigation Requirements Worksheet C.4-1 Page 3 of 4 Part 2 Partial Infiltration vs. No Infiltration Feasibility Screening Criteria Would infiltration of water in any appreciable amount be physically feasible without any negative consequences that cannot be reasonably mitigated? Criteria Screening Question Yes No Do soil and geologic conditions allow for infiltration in any appreciable rate or volume? The response to this Screening 5 Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D. Provide basis: X The infiltration rates are as follows: P-1: 0.2 in/hr (0.1 in/hr for factor of safety of 2.0) P-2: in/hr ( in/hr for factor of safety of 2.0) P-3: 0.01 in/hr (0.005 in/hr for factor of safety of 2.0) P-4: 0.04 in/hr (0.02 in/hr for factor of safety of 2.0) P-5: 0.83 in/hr (0.42 in/hr for factor of safety of 2.0) The test results indicate the geologic conditions allow for an appreciable rate. However, test P-1 and P-5 should not be relied on for design as these were performed in undocumented fill that will be removed and replaced as compacted fill during grading. 6 Can Infiltration in any appreciable quantity be allowed without increasing risk of geotechnical hazards (slope stability, groundwater mounding, utilities, or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2. X The site is underlain by undocumented fill, the Scripps Formation, and Granitic Rock. At the completion of grading, we expect the majority of the site will be underlain by compacted fill. The specific geologic or geotechnical hazard for this site is the potential for lateral migration of infiltration water to adjacent foundations, utilities, and behind retaining walls. The relatively slow infiltration test results is a reflection of the dense nature of the site bedrock soils. We expect that infiltration of storm water will be occluded and could potentially migrate laterally which could impact adjacent utilities and foundations. Partial infiltration is feasible provided precautions are taken. Basins should be deepened through the undocumented and compacted fill and into the native bedrock. In some areas this may not be feasible considering the depth of the fills. All basins should be set back at least 20 feet from existing and proposed new foundations and utilities. Additionally, basins should be deepened to a depth of at least 4 feet below the bottom of existing and proposed building foundations located within 50 feet of the basin area. All basins should include side liners and drains at the bottom of the basin. The pipe should be connected to the storm drain system. Additionally, the basin should have overflow protection devices. C-13

49 Worksheet C.4-1 Page 4 of 4 Appendix I: Forms and Checklists Criteria Screening Question Yes No Can Infiltration in any appreciable quantity be allowed without posing significant risk for groundwater related 7 concerns (shallow water table, storm water pollutants or other factors)? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: Groundwater was not encountered and is expected to be at least 50 feet below existing ground surface. Therefore, in our opinion, infiltration will not increase the risk of groundwater contamination. X Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates. Can infiltration be allowed without violating downstream 8 water rights? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: X Infiltration is not anticipated to have a negative impact on nearby water balance or discharge of contaminated groundwater to surface waters. Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates. Part 2 Result* If all answers from row 1-4 are yes then partial infiltration design is potentially feasible. The feasibility screening category is Partial Infiltration. If any answer from row 5-8 is no, then infiltration of any volume is considered to be infeasible within the drainage area. The feasibility screening category is No Infiltration. Partial Infiltration *To be completed using gathered site information and best professional judgment considering the definition of MEP in the MS4 Permit. Additional testing and/or studies may be required by the City to substantiate findings. C-14

50 G Little Flower Haven 11/1/2016 GWC P-1 Dia hole 10 inches Depth hole 42 inches Depth inst 40 inches Ht res 32 inches Wt lbs D = inches h calc = 5.58 inches h measured = 7 inches t (min) t (min) Wt (lbs) Wt (lbs) vol (ft 3 ) vol (in 3 ) Q (cipm) E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E+00 Q (cipm) h/r (h/r) 2 ((h/r) 2 +1) E E E E+00 Ksat 2.05E-01 iph P E+01 Q (cipm) 1.00E E E Time (min)

51 G Little Flower Haven 11/1/2016 GWC P-2 Dia hole 8 inches Depth hole 52 inches Depth inst 51.5 inches Ht res 32 inches Wt lbs D = inches h calc = 4.08 inches h measured = 8 inches t (min) t (min) Wt (lbs) Wt (lbs) vol (ft 3 ) vol (in 3 ) Q (cipm) E E E E E E E E E E E E E E E-02 Q (cipm) h/r (h/r) 2 ((h/r) 2 +1) E E E E+00 Ksat 6.52E-03 iph 1.50E+01 P E+01 Q (ipm) 5.00E E Time (min)

52 G Little Flower Haven 11/1/2016 GWC P-3 Dia hole 8 inches Depth hole 57 inches Depth inst 55.5 inches Ht res 27 inches Wt lbs D = inches h calc = 5.08 inches h measured = 7 inches t (min) t (min) Wt (lbs) Wt (lbs) vol (ft 3 ) vol (in 3 ) Q (cipm) E E E E E E E E E E E E E E E-02 Q (cipm) h/r (h/r) 2 ((h/r) 2 +1) E E E E+00 Ksat 1.21E-02 iph 2.00E+01 P E+01 Q (ipm) 1.00E E E Time (min)

53 G Little Flower Haven 11/1/2016 GWC P-4 Dia hole 8 inches Depth hole 53 inches Depth inst 52 inches Ht res 27 inches Wt lbs D = inches h calc = 4.58 inches h measured = 5 inches t (min) t (min) Wt (lbs) Wt (lbs) vol (ft 3 ) vol (in 3 ) Q (cipm) E E E E E E E E E E E E-01 Q (cipm) h/r (h/r) 2 ((h/r) 2 +1) E E E E+00 Ksat 4.20E-02 iph P E E+01 Q (ipm) 8.00E E E Time (min)

54 G Little Flower Haven 11/1/2016 GWC P-5 Dia hole 8 inches Depth hole 57 inches Depth inst 54.5 inches Ht res 27.5 inches Wt lbs D = inches h calc = 6.08 inches h measured = 7 inches t (min) t (min) Wt (lbs) Wt (lbs) vol (ft 3 ) vol (in 3 ) Q (cipm) E E E E E E E E E E E E E E E+00 Q (cipm) h/r (h/r) 2 ((h/r) 2 +1) E E E E+00 Ksat 8.28E-01 iph P E E+01 Q (ipm) 1.00E E Time (min)

55 APPENDIX D

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