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HomeMy WebLinkAboutCT 15-05; QUARRY CREEK PA R-3; STORM WATER MANAGEMENT PLAN; 2015-07-05STORM WATER MANAGEMENT PLAN FOR QUARRY CREEK PLANNING AREA R-3 City of Carlsbad, CA CT 15-05 / PUD 15-13 PREPARED FOR: PRESIDIO CORNERSTONE QC, LLC 4365 Executive Drive, Suite 600 SAN DIEGO, CA 92121 (858)-458-9700 ,„. PREPARED BY: BBSzO2 PLANNING ENGINEERING SURVEYING 3990 RUFFIN ROAD, SUITE 120 SAN DIEGO, CA 92123 858-560-1141 JOB NO. 71470.60 Er'''"7D July 15, 2015 JUL 7 CITY t_ PLANNiivu TABLE OF CONTENTS 1.0 Scope of Report 1.1 Declaration of Responsible Charge 2.0 Summary of Project Information 3.0 Pre-Project Site Conditions and Drainage Patterns Narrative 3.1 Site Development Constraints 4.0 Proposed Site Development and Drainage Patterns Narrative 4.1 Site Development Opportunities 5.0 Sources of Pollutants from the Existing Site Narrative 6.0 Project Hydrologic Location 7.0 Identification of 303(d) Impaired Receiving Waters 8.0 Identification of Pollutants Associated with Priority Project Category 9.0 Identification of Pollutants of Concern 10.0 Hydromodification Management Plan (HMP) Applicability Determination 11.0 Summary of HMP Compliance Approach 12.0 Permanent Source Control Best Management Practices (BMPs) 13.0 Identification of BMPs Applicable to Individual Priority Project Categories 14.0 Implementation of Site Design Low Impact Development (LID) Practices 15.0 Water Quality Treatment Calculations 16.0 Comparison of Water Quality Treatment Calculations 17.0 Relative Effectiveness of Project Treatment Facilities and Integrated Management Practices (IMPs) 18.0 Summary and Conclusion Narrative QUARRY CREEK R-3 Priority Development Project —SWMP SB&O INC. Page i 19.0 Figures Vicinity Map Proposed DMA Exhibit (map pocket) 20.0 Attachments City of Carlsbad Storm Water Standards Questionnaire Geotechnical Study reference Permanent BMP Certification Form (see Project Design Consultants [PDC]regional report) HMP Calculations (see PDC regional report) QUARRY CREEK R-3 Priority Development Project —SWMP SB&O INC. Page ii 1.0 Scope of Report A master or regional report, "Storm Water Management Plan Quarry Creek," dated March 19, 2015, was prepared for the Quarry Creek project by Project Design Consultants (PDC).The PDC regional report summarizes the storm water requirements for the entire Quarry Creek project, including bioretention basin 3-3 located northeast of the R-3 site,as show on sheet 10 of Drawing No. 484-5A.Furthermore, the PDC regional report details the design and modeling of the bioretention basin which includes continuous simulation modeling (SDI-1M), rather than the BMP sizing tables. This report is limited to documenting the following at the Planning Area R-3 (R-3) site: A)Site Design B)Source Control C)Tributary area and impervious area, including comparisons to those used in the PDC report D)Compliance and consistency with the assumptions and design parameters used in the PDC regional report. 1.1 Declaration of Responsible Charge This Storm Water Management Plan (SWMP)has been prepared under the direction of the following Professional Civil Engineer.The Professional Civil Engineer (Engineer) attests to the technical information contained herein, and to the engineering data upon which the following design, recommendations, conclusions and decisions are based.The selection, sizing, and design of the storm water treatment and other control measures in this report meet the requirements of the Regional Water Quality control Board Order R9-2007-0001 and subsequent amendments. QUARRY CREEK R-3 (LOT 3) /41(.(.e.oF Ess /040 ngineer-of-Wo PE Da e 4; 45)(— L. 5. c2(/)Allen Butcher Tr% Print Name <No.47107 M Exp.12-31 -15 SB&O, Inc.P,\,„..51/V Company oit• Df CALF QUARRY CREEK R-3 Priority Development Project —SWMP SB&O INC. Page 1 2.0 Summary of Project Information Item Project Information Project Name Quarry Creek Planning Area R-3 (Lot 3) Application Number(s)TBD Project Address Westerly terminus of existing Marron Road Assessor Parcel Number(s)167-040-11,-21 Total Project Area 6.60 AC. Proposed Project Description and Multifamily ResidentialLand Use Z Housing Development of 10 or more dwelling units r]Commercial Development of one acre and greater Heavy Industry of one acre and greater Automotive Repair Shop Applicable Priority Development ID Restaurant Project Categories Hillside Development greater than 5,000 square feet El Water Quality Environmentally Sensitive Area (WQESA) El Parking LotZStreet, Highways, and Freeways Retail Gasoline Outlets El Land Disturbance greater than one acre Redevelopment Project that Creates r -71 ElIncreases or NotReplaces >50 % Increases or of Replaces <50 %ofILIor Replaces 5,000 square feet of Impervious Surface Applicable Pre-Project Imp.Pre-Project Imp. Surface Surface Project Disturbed Area 6.598 AC/ 287,420 SF Predevelopment Impervious Area 0.000 AC/0 SF Proposed Impervious Area 3.565 AC/155,305 SF Proposed Pervious Area 3.033 AC / 132,115 SF Project Hydrologic Unit Watershed Tijuana Hydrologic Unit Project Hydrologic Soil Group El A B 111 C Z D Number of Discharge Locations 1 Location Required to Implement HMP Z Yes El No Number of HMP Compliance Points 1 Locations (POC-3-3 Per SWMP 14-13) Jack Robson Applicant Contact (858) 458-9700 jrobson@cornerstonecommunities.com QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 2 3.0 Pre-Project Site Conditions and Drainage Patterns Narrative The existing site, Planning Area R-3 (R-3), is part of the larger master plan development area Quarry Creek. The project is located in the City of Carlsbad (City), but is bordered to the east by the City of Oceanside. The project is situated west of College Boulevard, east of Interstate 5, and south of Haymar Drive. The first phase of Quarry Creek included preparation of the large sheet graded pads, and construction of public roads, public utilities, and the LID facilities required for both current and future phases of the project.The regional "Storm Water Management Plan Quarry Creek," dated March 19, 2015, by PDC, was prepared that used design assumptions to account for future development of the graded pad areas. This plan proved that the further design and development of the pad areas is consistent with the assumptions made in the regional SWMP. The R-3 area is located in the southeastern portion of the Quarry Creek development. Currently, R-3 is a large sheet graded pad approximately 6.60 acres in area. The pad was graded with a 1% slope to the northwest, directed towards a temporary sediment basin and temporary storm drain outlet. This temporary storm drain is connected to an existing Type B-5 storm drain cleanout. The existing cleanout is located near the northeast intersection of Adobe Springs Road and El Salto Falls Street. The existing cleanout is connected to a 30" RCP storm drain that outlets to a bio-retention/hydro-modification basin located northwest of the intersection of Adobe Springs Road and El Salto Falls Street. QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 3 3.1 Site Development Constraints Applicable Site Development Constraints Limited Available Hydraulic Head Z Impermeable Soils High Groundwater Contaminated Soils Geotechnical Instability Perimeter Conditions High Intensity Land Use Heavy Pedestrian Traffic Heavy Vehicular Traffic Restricted Right-of-Way Existing Easements Inadequate Down-Stream Drainage Infrastructure Public Safety Concerns Other: Comments: QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 4 4.0 Proposed Site Development and Drainage Patterns Narrative The R-3 area will be a multi-family residential development.A total of 88 units will be constructed, comprised of various attached product types (4-plex,5-plex, and 6-plex row home style buildings). R-3 is approximately 6.60 acres, with a net developable area ofapproximately 5.15 acres. This yields a net project density of 17.09 dwelling units per acre,which corresponds to High Density Residential (HDR)per Table 3-1 "Runoff coefficients for Urban Areas"of the San Diego County Hydrology Manual. Along with the construction of the multi-family style buildings, private driveways, walkways, and a public "scenic river walk" trail will be constructed.. The impervious portion of the site was calculated at 54%. This percentage is significantly lower than the percentage assumed in the regional SWMP. Drainage will still flow towards the northeast portion of the site, consistent with existing conditions.All runoff is collected and discharged to the existing Type B-5 cleanout and 30" RCP storm drain. The project will route runoff to the bio-retention basin 3-3 located northwest of the intersection of Adobe Springs Road and El Salto Falls Street,as intended in the regional SWMP. QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 5 4.1 Site Development Opportunities Applicable Site Development Opportunities E]Adequate Available Hydraulic Head Permeable Soils Groundwater Separation Geotechnical Stability Perimeter Conditions El Existing Natural Areas •Undevelopable Areas El Adequate Down Stream Drainage Infrastructure Other: Comments: QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 6 5.0 Sources of Pollutants from the Existing Site Narrative No known legacy pollutants QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 7 6.0 Project Hydrologic Location Hydrologic Unit Hydrologic Area Hydrologic Sub-Area Carlsbad 904.00 Buena Vista Creek 904.20 El Salto 904.21 QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 8 7.0 Identification of 303(d) Impaired Receiving Waters Pollutant(s) Causing Receiving Water Impairment to 303(d) Receiving Water Z Buena Vista Creek Selenium Sediment Toxicity NutrientsZBuena Vista Lagoon Indicator Bacteria Sedimentation/ Siltation QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 9 8.0 Identification of Pollutants Associated with Priority Project Category Priority Project Category General Pollutant Categories Sediment Nutrients Detached Residential Trash &Debris Development Oxygen Demanding Substances Oil &Grease Bacteria &Viruses Pesticides Sediment Nutrients r7ri Development Attached Residential Trash &Debris Oxygen Demanding Substances (if landscape exists on-site)® Oil &Grease (if uncovered parking areas exist on-site) Bacteria &Viruses Pesticides Sediment (if landscape exists on-site) Nutrients (if landscape exists on-site) Heavy Metals Organic Compounds (if uncovered parking areas exist on-site) 111 Commercial Development Trash &Debris Oxygen Demanding Substances (includes solvents) Oil &Grease Bacteria &Viruses (if land use includes food or animal waste products) Pesticides (includes solvents) Sediment Heavy Metals n Heavy Industry or Organic Compounds I—I Industrial Development Trash &Debris Oxygen Demanding Substances Oil &Grease QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 10 8.0 Identification of Pollutants Associated with Priority Project Category (continued) Priority Project Categories General Pollutant Categories Heavy Metals Organic Compounds (includes petroleum hydrocarbons and Automotive Repair Shop solvents) Trash &Debris Oil &Grease Trash &Debris Oxygen Demanding Substances Restaurants Oil &Grease Bacteria &Viruses Pesticides (if landscape exists on-site) Sediments Nutrients 111 Hillside Development Trash &Debris Oxygen Demanding Substances Oil &Grease Pesticides Sediments (if landscape exists on-site) Nutrients (if landscape exists on-site) AY Heavy Metals Parking Lots Trash &Debris Oxygen Demanding Substances (if landscape exists on-site) Oil &Grease Pesticides (if landscape exists on-site) Heavy Metals Organic Compounds Retail Gasoline Outlets Trash &Debris Oxygen Demanding Substances Oil &Grease Sediments Nutrients (if landscape exists on-site) Heavy Metals Organic Compounds (including petroleum hydrocarbons) Streets,Highways &Freeways Trash &Debris Oxygen Demanding Substances (includes solvents) Oil &Grease Bacteria &Viruses Pesticides (if landscape exists on-site) QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 11 9.0 Identification of Pollutants of Concern Pollutants Associated Pollutants Causing Impairment to 303(d)with Priority Project Pollutants of Concern Category Receiving Water(s) Chloride Z Sediment/Siltation0CopperSediment ToxicityZSedimentZNutrientsZSelenium Z Sediment O Phosphorus 0 Sulfates O Sediment 0 Total Nitrogen as N 0 Chloride 0 Sulfates Eutrophic 0 Total Dissolved SolidsZNutrients ®NutrientsZNutrientsElTotal Nitrogen as N O Phosphorus 0 Toxicity 0 Copper 0 Sulfates0Heavy Metals 0 Manganese 0 Total Dissolved Solids 1E1 Heavy Metals0Sediment Toxicity 0 Toxicity Eutrophic0Organic Compounds 0 Toxicity 0 Organic Compounds0SedimentToxic.q Eutrophic 0 Total Dissolved SolidsZTrash&Debris 0 Nutrients Z Trash &Debris0ToxicitySediment Toxicity n Eutrophic 0 SulfatesZOxygen Demanding Z Oxygen Demanding®Nutrients 0 Total Dissolved SolidsSubstances Substances0Phosphorus0Total Nitrogen as N EutrophicZOil &Grease ®Sediment Toxici 0 Toxicity Z Oil &Grease r- Enterococcus ®Indicator BacteriaZBacteria&Viruses 111 Eutrophic Z Bacteria &Viruses 0 Fecal Coliform 0 Total Coliform 0 Copper Z Sediment ToxicityZPesticides Eutrophic 0 Sulfates Z Pesticides0Phosphate0ToxicityElTotal Nitrogen as N QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 12 10.0 Hydromodification Management Plan (HMP) Applicability Determination NO 1. Is Project a4Priority Development Project? YESI IYES or N/A 2. Proper NO Redesign EnergyEnergy Dissipation Provided? 3. Does Project Increase Impervious Area? NO 4. Does ProjectNOIncrease Unmitigated Peak YES W Flows to My Outlet Location? YES 5. Does Project rE:341Directly Discharge to Exempt System? YES 6. Does Project NODirectly Discharge to Lagoon Area? YES 8. Does Stabilized YES 7. Does Project Directly Conveyance have Capacity Discharge to Stabilized Conveyance for Ultimate Ow?to Exempt System? NO NO 11 YES 9. Does Project .to highly '—1" Watershed? NO 11.Palomino Dcenainof Analysis YES la'IS Project Urban See HMP Soden 5.2 Disdwrging to - Guriveywx.e? NO1 12. Does Stabilized Conveyance Extend PastYES NODomain of Analysis and Eventually Discharge to LOW Susceptibility Stream? 13. Do CumulativeYES NOuture Impacts Represent < 3%tlImpervious Area HMP Exempt 1 Increase? 14. Hydromodification Controls Required End of Decision Matrix Go to Figure 6-2 of Decision Matrix Figure 6-1.HMP Applicability Determination QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 13 11.0 Summary of HMP Compliance Approach Not Applicable —Project Exempt from HMP requirements Determine/Identify Point(s)of Compliance Utilize SCCWRP Screening Tools to determine Stream Susceptibility Default to a High Susceptibility Stream (0.1Q2) El Utilize an appropriate HMP Sizing Tool to demonstrate HMP compliance Summary of Project Utilize HMP Sizing Tables to demonstrate HMP compliance HMP Compliance Approach [S]Utilize an approved Continuous Simulation Model and compare pre- project and mitigated post-project flows to demonstrate HMP compliance HEC-HMS HSPF IS]SDHM swmm Provide comprehensive, digital support data, calculation method and parameters, and calculation results on Compact Disk (CD) sufficient to duplicate study and support a RWQCB audit See "Storm Water Management Plan Quarry Creek" dated March 19, 2015, by Project Design Consultants,for HMP compliance documentation. QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 14 12.0 Permanent Source Control Best Management Practices (BMPs) Source Control BMP Applicable Implementation Requirements Z Provide prohibitive dumping placards and/or signage Z Post signage at public access points to deter prohibitive Z Storm Drain Inlet Labeling dumping Z Maintain legibility of placards and signage 0 Not Applicable Comment: O Materials placed in an enclosure (e.g. cabinet, shed, or similar structure that prevents contact with rain, runoff or spillage to the storm water conveyance system) O Protected by secondary containment structures (e.g. berms, dikes, or curbs) and paved or sufficiently impervious to Outdoor Material Storage Areas contain leaks and spills0The storage area is paved and sufficiently impervious to contain leaks and spills O Includes a roof or awning to minimize direct precipitation to the secondary containment area Z Not Applicable Comment: ma.Annsinn=_ QUARRY CREEK R-3 Priority Development Project —SWMP SB&O INC. Page 15 12.0 Permanent Source Control BMPs (continued) Source Control BMP Applicable Implementation Requirements 1 - 1 Paved with an impervious surface El Designed not to allow run-on from adjoining areas 111 Screened or walled to prevent off-site transport oftrash 111 Common Trash Enclosure and Recyclable Material Storage Use trash containers with attached lids to exclude rain and Areas maintain lids in closed position while not in use and/or include a roof or awning to minimize direct precipitation. Acknowledgment that installation of storm drain inlets or area drains in designated trash storage areas is prohibited Z Not Applicable Comment: Z Plant pest-resistant or well-adapted plant varieties such as drought tolerant and/or native plants Z Discourage pests by modifying the site and landscaping design [S]Distribute IPM educational materials to future occupants as Z Employ Integrated Pest part of the final engineering phase Operation and Management (IPM) Practices Maintenance Plan (O&M Plan) which addresses physical pest elimination techniques such as relying on natural enemies to consume pests, weeding, pruning, and etc.Emphasis placed on correct and limited use of pesticides as a last line of defense El Not Applicable Comment: QUARRY CREEK R-3 Priority Development Project —SWMP SB&O INC. Page 16 12.0 Permanent Source Control BMPs (continued) Source Control BMP Applicable Implementation Requirements [A Employ rain shutoff devices to prevent irrigation during and after precipitation El Design irrigation systems for the specific water requirements [E]Use of Efficient Irrigation of each landscape area Systems &Drought Tolerant [S]Use flow reducers or shutoff valves triggered by a pressure Landscape drop to control water loss in the event of broken sprinkler Design heads or lines El Provide water conservation educational materials to future occupants. 111 Not Applicable Properly connected to a sanitary sewer or, El An alternate method,as approved by the City Engineer 111 Interior Floor Drains and 111 Acknowledgment that direct connection of interior floor Elevator Shaft Sump Pumps drains and elevator shaft pumps to private or public storm drain or sanitary sewer is not permissible [Z]Not Applicable Comment: QUARRY CREEK R-3 Priority Development Project —SWMP SB&O INC. Page 17 12.0 Permanent Source Control BMPs (continued) Source Control RAW Applicable Implementation Requirements Prohibit vehicle washing Prohibit pressuring washing of parking surface in the parking garage and Provide adequate treatment control BMPs to treat runoff prior to discharge to an MS4 and Provide prohibitive dumping signage and floor drain marking; prominently displayed inside the parking garage and at the floor drains, respectively and; Implement dry clean-up methods for non-hazardous Interior Parking Garages accidental spillsEquippedwith Floor Drains Equipped with a clarifier or other pretreatment facility Properly connected to a sanitary sewer or, An alternate method,as approved by the City Engineer Acknowledgment that direct connection of interior floor drains and elevator shaft pumps to the sanitary sewer or storm water conveyance is not permissible Z Not Applicable Comment: El A pet waste station that includes eye level, post mounted signage which reads "pick-up after your pet" or similar approved language andZPet Use Areas A pet waste disposal receptacle equipped with a lid Not Applicable Comment: ———- QUARRY CREEK R-3 Priority Development Project— SWMP SB&O INC. Page 18 13.0 Identification of BMPs Applicable to Individual Priority Project Categories Individual Priority Project Applicable Best Management PracticeCategory Rural Swale System Urban Curb/Swale System Private Roads Dual Drainage System An alternate method,as approved by the City Engineer El Not Applicable Comment: Designed to drain into adjacent landscape prior to discharging to a storm water conveyance El Shared access [ZI Residential Driveways &Guest Flared or piano shaped entrance (single lane at street) Parking Wheelstrips (paving only under tires) Porous paving/Permeable surface Not Applicable Comment: QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 19 13.0 Identification of BMPs Applicable to Individual Priority Project Categories (continued) Individual Priority Project Applicable Implementation RequirementsCategory El Covered loading dock areas or, n Designed to preclude urban run-on and runoff 0 Containment method to isolate dock and facilitate pollutant removal, such as a shut-off valve and containment area 0 Dock Areas (Truck Wells) Equipped with a clarifier or other pretreatment facility 0 An alternate method,as approved by the City Engineer 0 Acknowledgement that direct connections to storm drains from depressed loading docks are prohibited Z Not Applicable Comment: •0 Located indoors and, 0 Designed to preclude urban run-on and runoff from adjacent areas0Self-contained bay drainage system (i.e. dead-end sump, with no outlet to offsite facilities) designed to capture all wash 0 Maintenance and Repair Bays water, leaks, and spills. The self-contained drainage system shall connect to a "dead end sump" for collection and proper disposalnAcknowledgement that connection ofmaintenance and repair bay drains to the sanitary sewer or storm water conveyance system is prohibited. Z Not Applicable Comment: QUARRY CREEK R-3 Priority Development Project —SWMP SB&O INC. Page 20 13.0 Identification of BMPs Applicable to Individual Priority Project Categories (continued) Individual Priority Project Applicable Best Management PracticeCategory n Paved with an impervious surface Self-contained to preclude urban run-on and runoff Preferably located indoors or, Covered with a roof or overhang Vehicle and Equipment Wash Equipped with a clarifier or other pretreatment facility Areas Properly connected to a sanitary sewer or, An alternate method,as approved by the City Engineer Acknowledgement that connection of vehicle and equipment wash areas to the storm water conveyance system is prohibited Z Not Applicable Comment: Cover or enclose areas ofthat are a source ofpollutants, Grade or berm the perimeter of the processing area to prevent run-on or runoff Sloped to a self-contained drainage system (i.e. "dead-end sump", with no outlet to offsite facilities) designed to capture all wash water, leaks, and spills. The self-contained drainage system shall connect to a "dead end sump" for collection and proper disposal Outdoor Processing Areas Equipped with a clarifier or other pretreatment facility Properly connected to a sanitary sewer or, An alternate method,as approved by the City Engineer Acknowledgement that installation of storm drain inlets in outdoor processing areas and connection to a storm water conveyance system is prohibited Z Not Applicable Comment: QUARRY CREEK R-3 Priority Development Project —SWMP SB&O INC. Page 21 13.0 Identification of BMPs Applicable to Individual Priority Project Categories (continued) Individual Priority Project Applicable Best Management PracticeCategory n Paved with an impervious PCC surface Ej Graded at a minimum slope to prevent pond formation 111 Separated by grade break, curb, or berm to prevent run-on 111 Covered with a canopy that extends a minimum of ten feet in each horizontal direction, for each pump, or alternatively; 111 Covered the fuel area with minimum dimensions equal to or greater than the area within the grade break or fueling area El Fueling Areas (defined as extending 6.5 feet from the corner of each fuel dispenser or the length at which each hose and nozzle assembly may be operated plus one foot, whichever is greater IE]The canopy shall not drain to the fueling area 111 Acknowledgement that connection of fueling areas to the sanitary sewer or storm water conveyance system is prohibited [Z1 Not Applicable Comment: [I Where landscaping is proposed in surface parking areas (both covered and uncovered), incorporate landscape areas into the drainage design El Retail and Surface Parking Areas Overflow parking (i.e. parking in excess ofthe minimum parking requirements for the project) may be constructed of permeable paving 1Z Not Applicable Comment: QUARRY CREEK R-3 Priority Development Project —SWMP SB&O INC. Page 22 13.0 Identification of BMPs Applicable to Individual Priority Project Categories (continued) Individual Priority Project Applicable Best Management PracticeCategory [S]Steep hillside areas disturbed by project development shall be landscaped with deep rooted, drought-tolerant plant species selected for erosion control and stabilized with Eg Steep Hillside Landscaping mulch, consistent with the statewide Water Conservation in Landscape Act Not Applicable Comment: QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 23 14.0 Implementation of Site Design Low Impact Development (LID) Practices LID Practice Applicable Design Characteristics Z Preserve natural drainage features Z Preserve existing trees and vegetation Minimize soil disturbance Z Clustering or concentrating development on the least Z Conserve Natural Areas environmentally sensitive areas; consistent with SUSMP §4.1 (e.g. developing on... previously graded areas, areas containing of non-native vegetation and etc.) Z Incorporation of open space Lot(s) An alternate method,as approved by the City Engineer Not Applicable Comment: Done as part ofthe Quarry Creek Master Plan. Z Minimize the impervious footprint by increasing building density and/or by incorporating multiple-storied architecture Z Construct streets, sidewalks, and parking lot drive aisles to minimum widths, provided public safety is not compromisedZIncorporate landscape buffers between sidewalks, streets, and other flatwork Z Minimize Impervious Surfaces Z Minimize impervious surfaces in landscape design; such as decorative or stamped concrete I - 1 Using permeable surfaces (porous concrete, pavers, asphalt) in overflow parking or low-traffic areas El An alternate method,as approved by the City Engineer El Not Applicable Comment: QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 24 14.0 Implementation of Site Design Low Impact Development (LID) Practices (continued) LID Practice Applicable Design Characteristic Z Minimize disturbance to natural drainages Z Convey runoff safely from the tops of slopes Vegetate slopes with native or drought tolerant landscape Z Protect Slopes and Channels Stabilize permanent channel crossings Install Energy Dissipaters An alternate method,as approved by the City Engineer Not Applicable Comment: QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 25 15.0 Water Quality Treatment Calculations Area Impervious area Landscape Area DMA Name SF AC SF AC SF AC R-3 287,420 6.598 155,305 3.565 132,115 3.033 01 6,342 0.146 0 0.000 6,342 0.146 BB 3-3 (offsite)23,656 0.543 23,656 0.543 0 0.000 02 (offsite)11,237 0.258 0 0.000 11,237 0.258 Totals 328,655 7.545 178,961 4.108 149,694 3.437 0. 65 CWQ 0.590 85th Percentile depth inch WQ Vol 10,505 CF 0.241 AF Provided Area 8,896 SF _Required Area 7,757 SF Computed % Sizing Area 4.587 Notes: 1) Cw0=Composite runoff factor per Section 4 of SUSMP=(impervious area'1+0.1`pervious area)/total area 2) WO Vo1=WQ 85th Percentile depth* Cwo* Area 3) Computed % sizing factor =Provided Basin Bottom Area with Sandy Loam (SF)/(Cwo • Area)*100 QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 26 16.0 Comparison of Water Quality Treatment Calculations SB&O Basin 3-3 Regional Report Design Assumptions Calculations % Difference Area (AC)7.5 7.55 101% Impervious Area (AC)4.81 4.108 85% CWQ 0.68 0.590 87% WQ Vol (AF)0.28 0.241 86% Provided Area (SF)8896 - Computed % Sizing Area 4 4.587 115% QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 27 17.0 Relative Effectiveness of Project Treatment Facilities rRelative Effectiveness of Project Treatment Facilities and IMPs Pollutants Grouped by Method of Transport Treatment Facility/IMP Coarse Pollutants Associated with Pollutants that tend to be Sediment Fine Particles During Dissolved Following and Trash Transport Treatment Z Bioretention IMP High High Medium Flow Through Planter IMP High High Medium El Infiltration IMP High High High El Conventional Vegetated Swale High Medium Low 111 Extended (Dry) Detention Basins High High Low 111 Media (Sand) Filter High High Low El Wet Pond High High Medium El Constructed Wetland High High Medium El Proprietary Vault/Tree Well High Medium Low 111 Proprietary Inlet Filter High Low Low QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 28 18.0 Summary and Conclusion Narrative This SWMP has identified this project as a Priority category that is required to implement Low Impact Development, Treatment Control, and hydromodification mitigation measures.The potential pollutants to be generated from this project have been identified and compared to the impairments of all downstream bodies of water leading to the Pacific Ocean.In order to mitigate for these potential pollutants, the R-3 area will discharge to bioretention basin 3-3 as defined and described in the regional SWMP. Basin 3-3 will also mitigate for potential hydromodification impacts to downstream receiving waters. This project is within and consistent with the assumptions used for the design of the applicable Integrated Management Practices set forth in the regional SWMP for the R-3 area. QUARRY CREEK R-3 Priority Development Project -SWMP SB&O INC. Page 29 Wes. . Ode t~e• 19.0 Figures Vicinity Map Proposed DMA Exhibit (map pocket) QUARRY CREEK R-3 Priority Development Project —SWMP SB&O INC. Page 30 cti Qi c'l M/RA0 EL CAM/NO .‘Z ‘/COSTA COLLEGE COUNTRY CLUB • .4.i 7--ci .R.CI(A /._;7 T 5 -- Z7 ^T-SITE ..HAMAR-- .5%.DR.LAKE tormRD. \t•MARRON '..1 RD. ,1 CAR.BAD,•k• sZ VICINITY MAP NOT 70 SCALE 7710AGIS EIR077-IERS PG.1107,GRID A-2 2006 EDMON 20.0 Attachments City of Carlsbad Storm Water Standards Questionnaire Geotechnical Study reference Permanent BMP Certification Form (see Project Design Consultants [PDC]regional report) HMP Calculations (see PDC regional report) QUARRY CREEK R-3 Priority Development Project —SWMP SB&O INC. Page 31 STORM WATER Development ServicesCity of STANDARDS Land Development Engineering441.6_QUESTIONNAIRE 1635 Faraday AvenueCarlsbad760-602-2750E-34 www.carlsbadca.gov INSTRUCTIONS: To address post-development pollutants that may be generated from development projects, the City requires that new development and significant redevelopment priority projects incorporate Permanent Storm Water Best Management Practices (BMP's)into the project design per the City's Standard Urban Stormwater Management Plan (SUSMP). To view the SUSMP, refer to the Engineering Standards (Volume 4, Chapter 2). Initially this questionnaire must be completed by the applicant in advance of submitting for a development application (subdivision, discretionary permits and/or construction permits). The results of the questionnaire determine the level of storm water standards that must be applied to a proposed development or redevelopment project. Depending on the outcome, your project will either be subject to 'Standard Stormwater Requirements'or be subject to additional criteria called 'Priority Development Project Requirements'.Many aspects of project site design are dependent upon the storm water standards applied to a project. Your responses to the questionnaire represent an initial assessment of the proposed project conditions and impacts.City staff has responsibility for making the final assessment after submission of the development application. If staff determines that the questionnaire was incorrectly filled out and is subject to more stringent storm water standards than initially assessed by you, this will result in the return of the development application as incomplete.In this case, please make the changes to the questionnaire and resubmit to the City. If you are unsure about the meaning of a question or need help in determining how to respond to one or more of the questions,please seek assistance from Land Development Engineering staff. A separate completed and signed questionnaire must be submitted for each new development application submission.Only one completed and signed questionnaire is required when multiple development applications for the same project are submitted concurrently. In addition to this questionnaire, you must also complete, sign and submit a Project Threat Assessment Form with construction permits for the project. Please start by completing Step 1 and follow the instructions.When completed,sign the form at the end and submit this with your application to the city. STEP 1 TO BE COMPLETED FOR ALL PROJECTS To determine if your project is a priority development project, please answer the following questions: YES NO 1.Is your project LIMITED TO constructing new or retrofitting paved sidewalks, bicycle lanes or trails that meet the following criteria: (1) Designed and constructed to direct storm water runoff to adjacent vegetated areas, or other non-erodible permeable areas; OR (2) designed and constructed to be hydraulically disconnected from X paved streets or roads; OR (3) designed and constructed with permeable pavements or surfaces in accordance with USEPA Green Streets guidance? 2.Is your project LIMITED TO retrofitting or redeveloping existing paved alleys, streets, or roads that are Xdesigned and constructed in accordance with the USEPA Green Streets guidance? If you answered "yes" to one or more of the above questions, then your project is NOT a priority development project and therefore is NOT subject to the storm water criteria required for priority development projects.Go to step 4, mark the last box stating "my project does not meet PDP requirements" and complete applicant information. If you answered "no" to both questions, then go to Step 2. E-34 Page 1 of 3 Effective 6/27/13 STORM WATER City of STANDARDS Development Services Land Development Engineering Faraday AvenueQUESTIONNAIRE1635.a„risbad760 -602-2750E-34 www.carlsbadca.gov STEP 2 TO SECO METED; OR•ALVNEW OR REDEVELOPMENT PROJECTS To determine if your project is a priority development project, please answer the following questions:YES NO 1.Is your project a new development that creates 10,000 square feet or more of impervious surfaces collectively over the entire project site?This includes commercial,industrial,residential,mixed-use,and public X development projects on public or private land. 2.Is your project creating or replacing 5,000 square feet or more of impervious surface collectively over the entire project site on an existing site of 10,000 square feet or more of impervious surface?This includes commercial,X industrial, residential, mixed-use, and public development projects on public or private land. 3.Is your project a new or redevelopment project that creates 5,000 square feet or more of impervious surface collectively over the entire project site and supports a restaurant?A restaurant is a facility that sells prepared Xfoods and drinks for consumption, including stationary lunch counters and refreshment stands selling prepared foods and drinks for immediate consumption. 4.Is your project a new or redevelopment project that creates 5,000 square feet or more of impervious surface collectively over the entire project site and supports a hillside development project?A hillside development Xproject includes development on any natural slope that is twenty-five percent or greater. 5.Is your project a new or redevelopment project that creates 5,000 square feet or more of impervious surface collectively over the entire project site and supports a parking lot.A parking lot is a land area or facility for the Xtemporary parking or storage of motor vehicles used personally for business or for commerce. 6.Is your project a new or redevelopment project that creates 5,000 square feet or more of impervious surface collectively over the entire project site and supports a street,road,highway freeway or driveway?A street,Xroad,highway,freeway or driveway is any paved impervious surface used for the transportation of automobiles, trucks, motorcycles, and other vehicles. 7.Is your project a new or redevelopment project that creates or replaces 2,500 square feet or more of impervious surface collectively over the entire site,and discharges directly to an Environmentally Sensitive Area (ESA)?"Discharging Directly to" includes flow that is conveyed overland a distance of 200 feet or less X from the project to the ESA, or conveyed in a pipe or open channel any distance as an isolated flow from the project to the ESA (i.e. not commingles with flows from adjacent lands).* 8.Is your project a new development that supports an automotive repair shop?An automotive repair shop is a facility that is categorized in any one of the following Standard Industrial Classification (SIC)codes:5013,X 5014, 5541, 7532-7534, or 7536-7539. 9.Is your project a new development that supports a retail gasoline outlet (RGO)?This category includes RGO's that meet the following criteria: (a) 5,000 square feet or more or (b)a project Average Daily Traffic (ADT) of X 100 or more vehicles per day. 10.1s your project a new or redevelopment project that results in the disturbance of one or more acres of land and are expected to generate pollutants post construction?X 11.1s your project located within 200 feet of the Pacific Ocean and (1)creates 2,500 square feet or more of Ximpervious surface or (2) increases impervious surface on the property by more than 10%? If you answered "yes" to one or more of the above questions, you ARE a priority development project and are therefore subject to implementing structural Best Management Practices (BMP's)in addition to implementing Standard Storm Water Requirements such as source control and low impact development BMP's.A Storm Water Management Plan (SWMP) must be submitted with your application(s) for development.Go to step 3 for redevelopment projects.For new projects, go to step 4 at the end of this questionnaire, check the "my project meets PDP requirements" box and complete applicant information. If you answered "no"to all of the above questions,you ARE NOT a priority development project and are therefore subject to implementing only Standard Storm Water Requirements such as source control and low impact development BMP's required for all development projects.A Storm Water Management Plan (SWMP)is not required with your application(s) for development.Go to step 4 at the end of this questionnaire, check the "my project does not meet PDP requirements"box and complete applicant information. E-34 Page 2 of 3 Effective 6/27/13 STORM WATER 4.14(....City of STANDARDS Development Services Land Development Engineering QUESTIONNAIRE 1635 Faraday AvenueCarlsbad760-602-2750E-34 www.carlsbadca.gov STEP 3 TO BE COMPLETED FOR REDEVELOPMENT PROJECTS THAT ARE PRIORITY DEVELOPEMENT PROJECTS ONLY Complete the questions below regarding your redevelopment project:YES NO Does the redevelopment project result in the creation or replacement of impervious surface in an amount of less than 50% of the surface area of the previously existing development? If you answered "yes," the structural BMP's required for Priority Development Projects apply only to the creation or replacement of impervious surface and not the entire development.Go to step 4,check the "my project meets PDP requirements" box and complete applicant information. If you answered "no," the structural BMP's required for Priority Development Projects apply to the entire development.Go to step 4, check the "my project meets PDP requirements" box and complete applicant information. STEP 4 7 CHECK THE APPROPRIATE BOX AND COMPLETE APPLICANT INFORMATION My project meets PRIORITY DEVELOPMENT PROJECT (PDP) requirements and must comply with additional stormwater criteria per the SUSMP and I understand I must prepare a Storm Water Management Plan for submittal at time of application. I understand flow control (hydromodification) requirements may apply to my project. Refer to SUSMP for details. My project does not meet PDP requirements and must only comply with STANDARD STORMWATER REQUIREMENTS per the SUSMP. As part of these requirements,I will incorporate low impact development strategies throughout my project. Applicant Information and Signature Box Address:End of existing Marron Road.Accessor's Parcel Number(s):167-040-11,-21 Applicant Name:Applicant Title:Cornerstone Communities VP a La/NA Pia Irvin t DeNtkoogni- Applica t Date:-7 -ILI •IS This Box for City Use Only City Concurrence:YES NO By: Date: Project ID: *Environmentally Sensitive Areas include but are not limited to all Clean Water Act Section 303(d) impaired water bodies; areas designated as Areas of Special Biological Significance by the State Water Resources Control Board (Water Quality Control Plan for the San Diego Basin (1994) and amendments); water bodies designated with the RARE beneficial use by the State Water Resources'Control Board (Water Quality Control Plan for the San Diego Basin (1994) and amendments); areas designated as preserves or their quivalent under the Multi Species Conservation Program within the Cities and County of San Diego; and any other equivalent environmentally sensitive areas which have been identified by the Copermittees. E-34 Page 3 of 3 Effective 6/27/13 UPDATE GEOTECHNICAL INVESTIGATION a ! 1 QUARRY CREEK,. CARLSBAD/OCEANSIDE, CALIFORNIA, ! ,, 1 GE:OCON'INcOp:13Oft.ATEpi t . , .I PREPARED FOR GEOTECHNICAL Ei\rsilkONMENTAL 1 i CORNERSTONE COMMUNITIES MATERIALS .! SAN DIEGO, CALIFORNIA ., ,. FEBRUARY 24, 2015 PROJECT NO. 07135-42-05 GEOCONINCORPORATED GEOTECHNiCAL el ENVIRONMENTAL fe MATERIALS *Wrr Project No. 07135-42-05 February 24, 2015 Cornerstone Communities 4365 Executive Drive, Suite 600 San Diego, California 92121 Attention:Mr. Jack Robson Subject:UPDATE GEOTECHNICAL INVESTIGATION QUARRY CREEK CARLSBAD/OCEANSIDE, CALIFORNIA Dear Mr. Robson: In accordance with your authorization,we are pleased to submit the results of our update geotechnical investigation for the proposed Quarry Creek project. Conclusions and recommendations presented herein are based on review of available published geotechnical reports and literature, observations during previous grading performed on the property for reclamation, previous subsurface geotechnical exploration and site reconnaissance of existing conditions. The eastern half of the property has been used for mining and crushing rock to produce commercial aggregates. As the result, the eastern half of the site is underlain by compacted fill,previously placed fill,undocumented fill,sedimentary,volcanic,and intrusive bedrock.Reclamation grading has occurred on this portion of the site. The western half of the site is in an ungraded natural condition. The accompanying report presents findings from our studies relative to geotechnical engineering aspects of developing the property.The site is considered suitable for the proposed improvements provided the recommendations of this report are followed. 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 4334A1- co ESS/0/ Ali Sadr t§St%0 Rodney C. Mikesell CEG 1778 it No.ins GE 2533 CERTIFIED 1ENGINEERING * % 0 t G. 1111/11;AS :RCM: dmc w GEOLOGIST •Z.r .)0 .),A ,c)(2s2533 rc en (4/del)Addressee `.OP COY—t OA.(2/del)The Corky McMillin Companies-*0 * ts>Attention:Mr. Don Mitchell 4)-z.r„ OF CO' 6960 Flanders Drive ei Son Diego, California 92121.2974 II Telephone 858.558.6900 11 Fox 858.5S8.6159 TABLE OF CONTENTS 1.PURPOSE AND SCOPE 1 2.PREVIOUS SITE USAGE AND GRADING 2 3.SITE AND PROJECT DESCRIPTION 3 4.SOIL AND GEOLOGIC CONDITIONS 3 4.1 Compacted Fill (Qcf)4 4.2 Undocumented Fill (Qudf)4 4.3 Previously Placed Compacted Fill (Qpcf)4 4.4 Previously Placed Fill (Qpf)5 4.5 Topsoil (Unmapped)5 4.6 Surficial Landslide Debris (Qlsf)5 4.7 Alluvium (Qal)5 4.8 Colluvium (Qc)6 4.9 Terrace Deposits (Qt)6 4.10 Santiago Formation (Ts)6 4.11 Salto Intrusive (Jspi)7 5.GROUNDWATER 7 6.GEOLOGIC HAZARDS 7 6.1 Faulting and Seismicity 7 6.2 Liquefaction 9 6.3 Flow Slide Potential 10 6.4 Landslides 10 7.CONCLUSIONS AND RECOMMENDATIONS 11 7.1 General 11 7.2 Excavation and Soil Characteristics 11 7.3 Subdrains 12 7.4 Grading 13 7.5 Surcharge Fill 16 7.6 Settlement Monitoring 16 7.7 Slope Stability 16 7.8 Seismic Design Criteria 18 7.9 Foundation and Concrete Slab-On-Grade Recommendations 19 7.10 Retaining Wall Recommendations 24 7.11 Detention Basin and Bioswale Recommendations 26 7.12 Site Drainage and Moisture Protection 27 LIMITATIONS AND UNIFORMITY OF CONDITIONS TABLE OF CONTENTS (Concluded) MAPS AND ILLUSTRATIONS Figure 1,Vicinity Map Figure 2 and 3, Geologic Map Figure 4, Geologic Cross Sections AA'through DD' Figure 5,Typical Canyon Subdrain Detail Figure 6, Typical Subdrain Cut-Off Wall Detail Figure 7, Typical Subdrain Outlet Headwall Detail Figure 8,Construction Detail for Lateral Extent of Removal Figure 9, Settlement Monument Figures 10 —14, Slope Stability Analysis Figure 15,Typical buttress Fill Detail Figure 16,Typical Retaining Wall Drain Detail APPENDIX A FIELD INVESTIGATION Figures A-1 —A-5, Logs of Large Diameter Borings Figures A-6 —A-27, Logs ofTrenches Figures A-28 —A-33, Logs of Small Diameter Borings Figures A-34 —A-39, Logs of Trenches (Geocon 9-10-09) APPENDIX B LABORATORY TESTING Table B-I, Summary of Laboratory Maximum Dry Density and Optimum Moisture Content Table B-II, Summary of Laboratory Direct Shear Test Results Table B-III,Summary of Laboratory Expansion Index Test Results Table B-IV, Summary of Laboratory Expansion Index Test Results Performed During Reclamation Grading Table B-V, Summary of Laboratory Water-Soluble Sulfate Test Results Table B-VI,Summary of Laboratory Water-Soluble Sulfate Test Results Performed During Reclamation Grading APPENDIX C SLOPE STABILITY ANALYSIS Table C-I, Summary of Soil Properties used for Slope Stability Analyses Table C-II, Summary of Slope Stability Analyses Figure C-1, Cut Slope Figures C-2 —C-3, Buttress Fill Slope APPENDIX D FLOW ANALYSIS Figure D-1,Stability Analysis for Flow Slide Potential Figure D-2,Stability Analysis to Determine Yield Coefficient APPENDIX E RECOMMENDED GRADING SPECIFICATIONS LIST OF REFERENCES UPDATE GEOTECHNICAL INVESTIGATION 1.PURPOSE AND SCOPE This report presents the results of an update geotechnical investigation for the proposed Quarry Creek development.The purpose of the geotechnical investigation is to evaluate surface and subsurface soil conditions and general site geology, and to identify geotechnical constraints that may impact development of the property. In addition, the purpose of this report is to provide foundation design criteria, concrete flatwork recommendations, retaining wall recommendations, excavation and remedial grading considerations that can be utilized in developing project budgets. The scope of this investigation also included a review of readily available published and unpublished geologic literature, aerial photographs and the following documents previously prepared for the property: 1.Preliminary Geotechnical Investigation,Quarry Creek II,Carlsbad/Oceanside,California, prepared by Geocon Incorporated, dated February 24, 2015 (Project No. 07135-42-03). 2.Foundation Report,Quarry Creek Bridge,Carlsbad,California,prepared by Geocon Incorporated, dated August 21, 2014 (Project No. 07135-42-04A). 3.Mass Grading Plansfor Quarry Creek, prepared by Project Design Consultants, undated. 4.Final Report of Testing and Observation Services During Site Grading,Quarry Creek, Carlsbad,California,prepared by Geocon Incorporated,dated April 4,2013 (Project No. 07135-42-02). 5.Final Report of Testing and Observation Services During Site Grading,Quarry Creek, Oceanside,California, prepared by Geocon Incorporated,dated March 11,2013 (Project No. 07135-42-02). 6.Update Geotechnical Investigation,Amended Reclamation Plan,Quarry Creek Refined Alternative 3,Carlsbad,California, prepared by Geocon Incorporated, dated September 10, 2009 (Project No. 07135 -42-01). 7.Limited Geotechnical Investigation to Evaluate Hardrock Constraints for Quarry Creek, Carlsbad,California,prepared by Geocon Incorporated,dated April 9,2004 (Project No. 07135-42-01B. 8.EIR —Level Soil and Geologic Reconnaissance Quarry Creek II Carlsbad/Oceanside, California,prepared by Geocon Incorporated,dated October 20,2011(Project No.07135- 42-01B). The site is located south of State Route 78 and west of College Boulevard in Carlsbad, California (see Vicinity Map, Figure 1). The eastern portion of the site has been graded as part of the reclamation process.Geocon Incorporated performed compaction testing and observation services during the grading operations. Project No. 07135-42-05 -I -February 24, 2015 References 4 and 5 are the as-graded reports prepared for reclamation grading. As-graded conditions are shown on the Geologic Map (Figures 2 and 3). Previous field investigations were conducted in 2012 (Reference 1)and 2004 (Reference 7). These investigations included large-diameter borings,small-diameter boring,and exploratory trenches. Pertinent information, including boring and trench logs and other details of the field investigations are presented in Appendix A. We tested selected soil samples obtained during the previous field investigations to evaluate physical properties for engineering analyses and to assist in providing recommendations for site grading. Details of the laboratory tests and a summary of the test results are presented in Appendix B and on the boring logs in Appendix A. The Geologic Map, Figures 2 and 3 also present the locations of the exploratory excavations. The base map used to generate Figures 2 and 3 is a CAD file ofReference 3. Other reports reviewed as part of this study are summarized on the List ofReferences at the end of this report. 2.PREVIOUS SITE USAGE AND GRADING The Quarry Creek property has undergone many years of mining, crushing, and screening to produce commercial aggregate products. The majority of previous mining activity occurred in the eastern and southern portions of the site. Mining waste products were placed in canyon or pit areas to reclaim quarry excavations. This resulted in placement of mostly undocumented fill in depressions,as well as some compacted fill. A former concrete batch plant and base-coarse crushing and screening plant operated by Hanson Aggregates occupied the central portion of the property. Other portions of the property were previously used for storage purposes, which include stockpiles of concrete and asphalt rubble, bioremediation stockpiles, and other materials. Reclamation grading of the previously mined area commenced in July 2011 and was completed in December 2012.During reclamation grading,undocumented fills were removed and replaced as compacted fill. Alluvium, within the drainage area,was removed to approximately 3 feet above groundwater elevation and replaced with compacted fill.Drop structures, levees, and rock revetment slopes were constructed along and in Buena Vista Creek drainage. Reclamation grading has resulted in removal of undocumented fill and replacement with compacted fill on the south side of Buena Vista Creek and majority of the areas north of the creek. Reclamation grading resulted in large sheet- graded pads on the eastern half of the property on both the north and south sides of Buena Vista Creek. The western portion of the property has remained in an ungraded condition. Project No. 07135-42-05 -2 -February 24, 2015 3.SITE AND PROJECT DESCRIPTION The overall site slopes northward, southward, and westward, following the east-west natural drainage of Buena Vista Creek valley and its tributaries.The original valley-slope topography has been lowered by quarry operations and then regarded to the current sheet grade elevations during reclamation grading. Mining of rock in the northeast quadrant has created near-vertical rock slopes. The cut has exposed fractured rock, which is very strong and considered stable in its temporary steep condition.Recommendations for a permanent slope condition are provided in the slope stability section of this report. Slopes on the south side of the valley have been graded to permanent 2:1 (horizontal:vertical) cut slopes with benches, bench-drains and brow-ditches. On the north side of the property, reclamation grading has resulted in 2:1 cut slopes.Elevations in the eastern half of the property vary from approximately 80 feet Mean Sea Level (MSL) to above 300 feet MSL in open-space areas.Sheet graded pad elevations vary from approximately 105 to 115 feet MSL.On the western ungraded portion of the site, existing site elevations vary from approximately 80 feet MSL to 160 feet MSL. Review of the grading plan for Quarry Creek indicates regrading in the eastern half ofthe property will generally consist of cuts up to approximately 35 feet and fills of 15 feet,respectively.Within the ungraded western portion, cuts and fills up to 40 feet and 30 feet, respectively will occur to create large sheet-graded pads.Development will also include the construction of a bridge across the creek, roadways, and utilities.A report specific to the bridge has been provided separately (see Reference 2). Final plans for development have not yet been completed,however,we understand plans are to construct 3-story multi-family buildings,2-story single family attached units,affordable housing units,and a community facility.Plans include street improvements,utilities,and several neighborhood parks. Several water quality basins are planned within the development. The site description and proposed development are based on a site reconnaissance and review of the available plans.If development plans differ significantly from those described herein, we should be contacted for review and possible revisions to this report. 4.SOIL AND GEOLOGIC CONDITIONS Eight surficial soil deposits and four geologic formations were encountered and/or mapped on the property.Surficial soil deposits include undocumented fill,compacted fill,previously placed fill, topsoil (unmapped),surficial landslide debris,alluvium,and colluvium. Formational units include: Quaternary-age Terrace Deposits; Tertiary-age Santiago Formation; and Jurassic-age Salto Intrusive rock.Mapped limits of the geologic units are shown on the Geologic Maps (Figures 2 and 3). Project No. 07135-42-05 -3 -February 24, 2015 Geologic Cross Sections are presented on Figure 4.The surficial soil types and geologic units are described below. 4.1 Compacted Fill (Qcf) Compacted fill placed during reclamation grading exists across the eastern half of the property. Observation and compaction testing of the fill has been performed by Geocon Incorporated. Report documenting compaction tests and as-graded conditions were prepared in 2013 (see References 4 and 5).The fill is predominately comprised of silty to clayey sand with varying amounts of rock fragments,soil rock fills,and windrows of oversize rock and concrete.A 10-foot hold-down for oversize rock was provided during reclamation grading.However,in the southwest portion of the reclamation grading area, the hold down was raised to 7 feet below finish grade.Compacted fill is considered suitable for support of additional fill and structural loads. 4.2 Undocumented Fill (Qudf) Undocumented fill exists in the northeast portion of the property beyond the reclamation grading limit and within the existing access road from Haymar Drive. The majority of this undocumented fill will likely be removed to achieve sheet grades based on proposed cuts shown on the project grading plans. However, we expect some remedial grading will be needed below proposed cut elevations to completely remove undocumented fill. A small amount of undocumented fill also exists just west of the graded reclamation parcels near the central portion of the project.Undocumented fill is unsuitable in its present condition, and will require removal and recompaction to support additional fill or structural improvements. Oversize materials encountered during remedial grading may require breaking down and special placement procedures in deeper fill areas. In the southwest portion of Lot 2,a limited amount of undocumented fill was left in-place during reclamation grading due to the presence of groundwater.Based on our observations during reclamation grading and potholes performed, we expect less than 3 to 5 feet of fill was left below groundwater in some areas.We do not expect the presence of the undocumented fill will impact future development. 4.3 Previously Placed Compacted Fill (Qpcf) Limited areas in the northeast and southeast portions of the property are underlain by previously placed compacted fill (see Geologic Map).According to a report by Ninyo and Moore (dated August 31, 2000), most of the approximately 10 feet of documented fill in the bottom of the northern pit area had been placed between approximately 1988 and 2000.The report describes the fill Project No. 07135-42-05 -4 -February 24, 2015 as ... interlayered, medium dense to dense,clayey and silty sand, clayey gravel and stiffsandy clay. Portions of the compacted fill were buried beneath stockpiles of oversize shot-rock that was removed during reclamation grading. The upper approximately 3 to 5 feet of previously placed compacted fill was removed during reclamation grading and recompacted. Previously placed compacted fill associated with the development of the eastern quarry (Wal-Mart shopping center)encroaches into the southeastern portion of the property.These materials were partially removed and recompacted during reclamation grading operations.Based on observations during reclamation grading, the fill appears to be relatively dense with adequate moisture content and considered suitable for support of structural improvements. 4.4 Previously Placed Fill (Qpf) Previously placed fill exists near Haymar Drive and Highway 78 along the northern property boundary. The approximate limit of the previously placed fill is shown on Figure 2 (Geologic Map). These soils should not impact future development of the property. 4.5 Topsoil (Unmapped) Portions of the western side of the site are irregularly blanketed by 1 to 3 feet of topsoil consisting of loose, porous, dark brown, silty to clayey, fine sand. Topsoil is compressible and expansive, and will require removal and recompaction within areas of planned development. Expansive clays should be placed in deeper excavations during grading. 4.6 Surficial Landslide Debris (Qlsf) Several suspicious surficial landslides are mapped within the western portion of the site,along the south banks of the Buena Vista Creek basin. Due to the limited access to these areas,subsurface investigation was not practical at this time. Their existence will be verified when access is available or during the grading operations.Trench T-5 was excavated at one of these areas and showed approximately 5 feet of sandy clay material overlying bedrock formation.The surficial landslide debris,if they exist, are considered unsuitable for receiving fill or structures and require removal. 4.7 Alluvium (Qal) Alluvial deposits are present within the major east-west drainage of Buena Vista Creek,as well as in the northeastern and southwestern tributary canyons that converge with Buena Vista Creek in the central portion of the site.The alluvial soils generally consist of loose,porous dark gray to dark brown, very clayey, fine to medium sand, and clayey sand and silt with occasional layers of slightly silty sand.Areas of deepest alluvium are located in the central portion of the site adjacent to the Project No. 07135-42-05 -5 -February 24, 2015 original channel of Buena Vista Creek and its tributaries.The alluvium is compressible and not suitable for support of additional fill and/or structural loads and will require partial (dependent upon groundwater depths)to complete removal.Remedial grading of the alluvium along the north and south sides of the main Buena Vista Creek drainage has occurred during the reclamation grading. Alluvium is expected to be encountered along the toe of the south facing fill slope at the west end of the property. 4.8 Colluvium (Qc) Colluvial deposits were encountered in the southwest portion of the site mostly along the sides of the draining tributary canyons. Colluvium is comprised of approximately 4 to 6 feet of loose dark brown, very clayey to silty, fine sand. Due to the loose unconsolidated condition of the colluvium, removal and recompaction will be required to provide suitable support for placement of compacted fill or structural improvements. 4.9 Terrace Deposits (Qt) Extensive and thick river terrace deposits consisting of medium-dense to dense, light reddish-brown to olive-brown, gravelly, silty to clayey, medium to coarse sand to cohesionless sand with occasional layers of silty clay are present in the western and southwest portions of the site.Except near depositional contacts (or unconformities)with older formations,this unit is typically massive to horizontally bedded,relatively dense and exhibits low compressibility characteristics.Terrace Deposits are most prevalent in the southwestern portion of the site. The sandy zones are suitable for support of fill and/ or structural loads in their present condition. The clayey zones, however, possess low shear strength and high expansion potential. Our large diameter boring LB-2 performed in the proposed cut slope located at the southwest boundary,adjacent to Simsbury Court,encountered materials consists of interbedded silty sand, cohessionless sand and clay layers which arc occasionally partially remolded.We recommend a stability buttress be constructed along this cut slope to provide adequate slope stability. 4.10 Santiago Formation (Ts) The Eocene-aged Santiago Formation, consisting of dense, massive bedded light brown to greenish- gray sandstones and thin interbedded siltstones is present in the north -central and south-central portions of the site.The Santiago Formation is generally granular and possesses suitable geotechnical characteristics in either an undisturbed and/or properly compacted condition. However, the occurrence of clayey siltstones and claystone layers in this unit may generate moderate to highly Project No. 07135-42-05 -6 -February 24, 2015 expansive materials,or localized expansive zones at grade.Where practical,clayey zones of the Santiago Formation should be placed at least 3 feet below proposed subgrade elevations. 4.11 Salto Intrusive (Jspi) The Jurassic-aged Salto Intrusive consists of a steeply jointed,dark gray,very strong tonalite to gabbro rock considered to be older than the Peninsular Range Batholith and more closely related to the formation of the Santiago Peak Volcanics (Larsen,1948). This granitoid bedrock unit is present in the northeast and southeast corners of the property and is the predominant geologic unit that has been mined for aggregate on the property. Typically, this bedrock unit outcrops along the eastern or southeastern boundary of the site, or is covered by fill in the central portions of the site. Exploratory excavations encountered mostly buried intrusive rock that exhibited a variable weathering pattern ranging from intensely weathered and fractured material near contacts with the overlying sedimentary rocks, to fresh, extremely strong crystalline rock within quarried areas. 5.GROUNDWATER Groundwater was encountered in the major lower elevation drainage areas of Buena Vista Creek and its tributaries at elevations between 70 to 80 feet MSL.Depth of groundwater is subject to fluctuation from natural seasonal variations.The relationship between alluvial removals and the position of groundwater table and time of year remedial grading is performed are discussed in the Conclusions and Recommendations section of this report. 6.GEOLOGIC HAZARDS 6.1 Faulting and Seismicity Review of geologic literature, previous geotechnical reports for the property, and observations during our current field investigation indicates no active faults traverse the property. One fault was observed in Salto Intrusive rock across the quarry slope in the northeast corner of the property. However,an exploratory trench excavated through the Tertiary Santiago Formation across the fault confirmed the fault did not displace the Eocene-age sedimentary unit. As such, the fault is considered inactive and not a constraint to the property. According to the results of the computer program EZ-FRISK (Version 7.62),8 known active faults are located within a search radius of 50 miles from the property. The nearest known active fault is the Newport-Inglewood-Rose Canyon Fault Zone, located approximately 6 miles east of the site 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 Project No. 07135-42-05 -7 -February 24, 2015 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 Fault are 7.5 and 0.34 g,respectively. We used Boore-Atkinson (2008) NGA USGS2008, Campbell-Bozorgnia (2008) NGA USGS 2008, and Chiou-Youngs (2008) NGA acceleration-attenuation relationships in the calculation of the peak ground accelerations (PGA).Table 6.1.1 lists the estimated maximum earthquake magnitudes and PGA's for the most dominant faults for the site location calculated for Site Class D as defined by Table 1613A.5.3 ofthe 2010 CBC. TABLE 6.1.1 DETERMINISTIC SPECTRA SITE PARAMETERS Maximum Peak Ground Acceleration Distance EarthquakeFault Name from Site Boore-Campbell-Chiou- (miles)Magni)tude Atkinson Bozorgnia Youngs(Miv 2008 (g)2008 (g)2008 (g) Newport-Inglewood-Rose Canyon 6 7.50 0.30 0.26 0.34 Elsinore 21 7.85 0.21 0.15 0.19 Coronado Bank 23 7.40 0.18 0.12 0.14 Palos Verdes Connected 23 7.70 0.19 0.13 0.16 San Joaquin Hills Thrust 35 7.10 0.18 0.10 0.09 Earthquake Valley 42 6.80 0.13 0.09 0.11 San Jacinto 45 7.88 0.13 0.08 0.10 Chino 47 6.80 0.08 0.05 0.05 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 fault slip rate.The program accounts for 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 USGS2008,Campbell-Bozorgnia (2008)NGA USGS 2008,and Chiou-Youngs (2008)in the Project No. 07135 -42-05 -8 -February 24, 2015 analysis.Table 6.1.2 presents the site-specific probabilistic seismic hazard parameters including acceleration-attenuation relationships and the probability of exceedence for Site Class D. TABLE 6.1.2 PROBABILISTIC SEISMIC HAZARD PARAMETERS Peak Ground Acceleration Probability of Exceedence Boore-Atkinson,Campbell-Bozo rgnia,Chiou-Youngs, 2008 (g)2008 (g)2008 (g) 2% in a 50 Year Period 0.52 0.42 0.47 5% in a 50 Year Period 0.39 0.32 0.35 10% in a 50 Year Period 0.31 0.25 0.27 The California Geologic Survey (CGS)provides a computer program that calculates the ground motion for a 10 percent of probability of exceedence in 50 years based on the average value of several attenuation relationships.Table 6.1.3 presents the calculated results from the Probabilistic Seismic Hazards Mapping Ground Motion Page from the CGS website. TABLE 6.1.3 PROBABILISTIC SITE PARAMETERS FOR SELECTED FAULTS CALIFORNIA GEOLOGIC SURVEY Calculated Acceleration (g) Calculated Acceleration (g)Calculated Acceleration (g) Firm Rock Soft Rock Alluvium 0.27 0.29 0.33 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 he evaluated in accordance with the California Building Code (CBC) guidelines. 6.2 Liquefaction Liquefaction analyses were performed during Geocon's 2009 report for reclamation grading. Results of the analyses indicate alluvial deposits below the groundwater should not liquefy for the design level acceleration. However, design accelerations for under current building codes have significantly increased over the last several years.Under current design accelerations,portions of the alluvium below groundwater could experience liquefaction.Liquefaction,should it occur,is expected to be limited to the area within the existing Buena Vista Creek drainage,and in the tributary drainage Project No. 07135-42-05 -9 -February 24, 2015 southwest of the site. With respect to the alluvium left in place within Lot 2, the alluvium is likely less than 10 feet thick,has been surcharged with approximately 15 to 20 feet of fill, will receive an additional 5 feet of fill to achieve proposed sheet grades, and will be surcharged with an additional 5 feet of fill during regrading (see Section 7.5 of this report). In our opinion, liquefaction,if it were to occur in this area would not cause surface manifestations (i.e.,sand boils).Settlement,should it occur is expected to be relatively uniform and less than 1 -inch total.We estimate differential settlement as a result of liquefaction to be 1/2-inch or less. 6.3 Flow Slide Potential We analyzed flow slide potential for liquefaction conditions along the channel bank. We performed a slope stability analysis using residual shear strength parameters for the potentially liquefiable soils. Residual shear strengths were determined using information provided in Recommended Procedures for Implementation of DMG Special Publication 117 Guidelines for Analyzing and Mitigating Liquefaction in California. It is our opinion that there is a low potential for flow slide impacts to structures at the locations shown on Figure 2.The results of the stability analysis are shown graphically in Appendix D (see Figures D-1 and D-2). 6.4 Landslides Review of 1995 published landslide maps of the California Geological Survey (formerly the Division of Mines and Geology) and a previous geotechnical report by Ninyo and Moore (August 23, 2000), suggested the presence of suspected landslide deposits in the southwest quadrant of the site. However,observations of intact outcrops and current subsurface investigation confirmed that the landslide does not exist.Several suspicious surficial landslides are mapped along the south bank of the creek. These areas were not accessible for subsurface investigation. These potential landslides, even if confirmed, should not have significant impact on the proposed development. Project No. 07135-42-05 -10 -February 24, 2015 7.CONCLUSIONS AND RECOMMENDATIONS 7.1 General 7.1.1 From a geotechnical engineering standpoint, it is our opinion that the site is suitable for the proposed development, provided the recommendations presented herein are implemented in design and construction of the project. 7.1.2 Soil conditions identified during this study that may impact development include compressible surficial soils (undocumented fill,alluvium,colluvium,surficial landslide debris and topsoil)that will require remedial grading.Undocumented fill may contain large rock fragments that require special placement procedures. 7.1.3 The property is approximately 7 miles from the Newport Inglewood/Rose Canyon Fault. It is our opinion active and potentially active faults do not extend across or trend toward the site.Risks associated with seismic activity consist of the potential for strong seismic shaking.Building setbacks will not be required for the planned development due to faulting. 7.1.4 Several potential surficial landslides are mapped along the north-facing slope within the western portion of the site. Due to the limited access, these areas could not be reached for subsurface investigation.If encountered during the grading operations, total removal of the slide debris within the grading area is recommended. 7.1.5 Subsurface conditions observed may be extrapolated to reflect general soil/geologic conditions; however, some variations in subsurface conditions between trench and boring locations should be anticipated. 7.2 Excavation and Soil Characteristics 7.2.1 Excavation of the Terrace Deposits,Santiago Formation and weathered portion of the Salto Intrusive is expected to require a heavy to very heavy effort to excavate.Less weathered and fresh Salto Intrusive bedrock may require blasting or specialized rock breaking techniques to efficiently excavate and handle.Very heavy effort with possible refusal is expected for excavations into the volcanic and intrusive rocks. Oversize material may be generated which would require special handling or exportation from the site. 7.2.2 The soil encountered in the field investigation is considered to be "expansive" (expansion index greater than 20)as defined by 2013 California Building Code (CBC)Section 1803.5.3.Table 7.2 presents soil classifications based on the expansion index. Based on Project No. 07135-42-05 -11 -February 24, 2015 the results of our laboratory testing,presented in Appendix B,we expect the on-site materials will possess a "very low"to "very high" expansion potential (Expansion Index of 20 and greater). TABLE 7.2 EXPANSION CLASSIFICATION BASED ON EXPANSION INDEX ASTM 4829 AND 2013 CBC Expansion Index (EI)Expansion Classification 2013 CBC ASTM 4829 Expansion Classification 0 —20 Very Low Non-Expansive 21 —50 Low 51 —90 Medium Expansive 91 —130 High Greater Than 130 Very High 7.2.3 We performed laboratory tests on samples of the site materials to evaluate the percentage of water-soluble sulfate content. Results from the laboratory water-soluble sulfate content tests are presented in Appendix B and indicate that the on-site materials at the locations tested possess "negligible" sulfate exposure to concrete structures as defined by 2013 CBC Section 1904 and ACI 318-08 Sections 4.2 and 4.3. We recommend the requirements set forth by 2013 CBC Section 1904 and ACI 318 be followed when determining the type of concrete to be used.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. 7.2.4 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 arc planned. 7.3 Subdrains 7.3.1 Canyon subdrains are recommended to mitigate the potential for adverse impacts associated with observed and potential seepage conditions and to collect perched water that migrates along the contact between natural ground and fill surfaces. Figure 5 presents a typical canyon subdrain detail.Recommended subdrain locations are depicted on the Geologic Map, Figures 2 and 3. Project No. 07135-42-05 -12 -February 24, 2015 7.3.2 The final 20-foot segment of a subdrain should consist of non-perforated drainpipe. At the non-perforated/perforated interface,a seepage cutoff wall should be constructed on the downslope side of the junction in accordance with Figure 6.Subdrains that discharge into a natural drainage course or open space area should be provided with a permanent headwall structure in accordance with Figure 7. 7.3.3 Final grading plans should show the location of the proposed subdrains. Upon completion of remedial excavations and subdrain installation, the project civil engineer should survey the drain locations and prepare an "as-built"map depicting the existing conditions. The final outlet and connection locations should be determined during grading.The grading contractor may consider videoing the subdrains shortly after burial to check proper installation and to check that the pipe has not been crushed.As a minimum,we recommend the subdrain for the buttress fill be videoed. The contractor is responsible for the performance of the drains. 7.4 Grading 7.4.1 All grading should be performed in accordance with the Recommended Grading Specifications contained in Appendix E.Where the recommendations of Appendix E conflict with this section of the report,the recommendations of this section take precedence. 7.4.2 Prior to commencing grading,a preconstruction conference should be held at the site with the owner or developer,grading contractor, civil engineer, and geotechnical engineer in attendance. Special soil handling and/or the grading plans can be discussed at that time. 7.4.3 Grading should be performed in conjunction with the observation and compaction testing services of Geocon Incorporated.Fill soil should be observed on a full -time basis during placement and tested to assess in -place dry density and moisture content. 7.4.4 Site preparation should begin with removal of all deleterious material and vegetation. The depth of removal should be such that material exposed in cut areas or soil to be used for fill is relatively free of organic matter.Deleterious material generated during stripping and/or site demolition should be exported from the site. 7.4.5 Undocumented fill,topsoil,colluvium,alluvium and landslide debris within areas of planned grading should be removed to firm natural ground and properly compacted prior to placing additional fill and/or structural loads. The actual extent of unsuitable soil removals should be determined in the field by the soil engineer and/or engineering geologist. Overly Project No. 07135-42-05 -13 -February 24, 2015 wet surficial materials, where encountered,will require drying and/or mixing with drier soils to facilitate proper compaction. 7.4.6 Alluvium should be removed down to competent formational bedrock or to within approximately 3 feet of the groundwater table, whichever occurs first. During excavation of the alluvium,test pits should be periodically excavated to determine groundwater depths. Dewatering and special equipment such as swamp cats, excavators, and top loading operations may be required to excavate the alluvium. Removals at the toe of slopes along the drainage channel at the southwest corner of the property should extend out at a 1:1 plane from the toe to the bottom of the removal.A typical lateral extent of removal is shown on Figure 8. 7.4.7 Graded areas may expose volcanic/intrusive rock at finish grade.The presence of hard rock may impact future development. We recommend hard rock be undercut to a depth of at least 5 feet below finish grade in building pads and 2 feet below utilities and a soil cap replaced. 7.4.8 After removal of unsuitable material as recommended above, the base of overexcavations and natural ground surfaces (including previous compacted fill soil) to receive additional fill should be scarified approximately 12 inches, moisture conditioned, and compacted. 7.4.9 The site should then be brought to final subgrade elevations with structural fill compacted in layers.In general,soils native to the site are suitable for re-use as fill if free from vegetation, debris and other deleterious material.Layers of fill should be no thicker than will allow for adequate bonding and compaction.All fill,backfill,and scarified ground surfaces should be compacted to a dry density of at least 90 percent of maximum dry density near to slightly above optimum moisture content,as determined in accordance with ASTM Test Procedure D 1557.Fill areas with in-place density test results indicating moisture contents less than optimum will require additional moisture conditioning prior to placing additional fill. 7.4.10 To reduce the potential for differential settlement, it is recommended that the cut portion of building pads with cut-fill transitions be undercut at least 3 feet and replaced,where practical, with "very low-to "medium" expansive compacted Fill soils. 7.4.11 Cut pads exposing concretions, cemented material, or expansive soil should be undercut at least 3 feet and replaced with properly compacted "very low" to "medium" expansive soil to facilitate excavation of foundations and shallow utilities. Project No. 07135-42-05 -14 -February 24, 2015 7.4.12 Undercuts (overexcavations)performed on pads with cut-fill transitions,cemented sandstone, hard rock or expansive soil materials at grade should be undercut at a gradient of 1 percent toward the street or toward the deepest fill area to provide drainage for moisture migration along the contact between the native soil and compacted fill. 7.4.13 The on-site soil is suitable to be used as fill if relatively free of debris and organic material. The depth of removal should be such that dense natural ground is exposed at the base of the overexcavation. 7.4.14 Grading should be performed such that highly expansive soils are placed in the deeper fill areas and outside of slope zones.Materials within 3 feet of finish grade on lots and the upper 12 inches of subgrade within streets, where practical, should consist of very low to medium expansive soils (soil with an Expansion Index less than 90). 7.4.15 Cut and fill slopes should be constructed at an inclination of 2:1 (horizontal to vertical) or flatter. An approximately 15-foot-high 1.5:1 cut slope in the Salto Intrusive is planned in the southeast portion of the property and an approximately 30-foot-high 1.5:1 cut slope in - Santiago Formation is planned at the northeast portion. These 1.5:1 slopes are acceptable provided they are free of adverse bedding. It is recommended that the slope excavations be observed during grading by a representative of Geocon Incorporated to check that soil and geologic conditions do not differ significantly from those anticipated and adverse bedding does not exist. 7.4.16 All fill slopes should be constructed of granular material and compacted out to the face of the finish slope.If complete removals cannot be performed outside the toe of slopes due to environmentally sensitive areas and/or groundwater conditions,Geocon Incorporated should be consulted to provide recommendations. 7.4.17 Excavations in cemented zones of formational units will likely generate oversize rock chunks.Oversized materials can be placed in fill areas in accordance with the recommendations contained within the Recommended Grading Specifications in Appendix D.Oversize materials (rocks or hard lumps in excess of 12 inches in least dimension)should be kept at least 10 feet below proposed finish grade within building pads and at least 2 feet below the deepest utility within street right-of-ways. Modifications to the hold down depths can be made at the owner's desecration. Project No. 07135-42-05 -15 -February 24, 2015 7.5 Surcharge Fill 7.5.1 In Lot 2 where undocumented fill and alluvium were left in-place below groundwater, we recommend a surcharge fill height of at least 5 above finish pad grade be placed.The approximate area of recommended surcharge is shown on Figure 2.The top of the surcharge fill should extend out to a horizontal distance of at least 10 feet beyond the limits where alluvium was left in-place. We recommend the bottom 1 -foot of the surcharge fill be placed and compacted as structural fill.This will result in compacted fill at finish grade once settlement of the underlying alluvium occurs. 7.6 Settlement Monitoring 7.6.1 Settlement monitoring is recommended where surcharge fill is placed.Once rough pad grade is attained,we recommend surface monuments be installed to measure settlement. The locations and number of monuments should be determined by Geocon once building pad locations are known.A typical surface settlement monument detail is presented as Figure 9. 7.6.2 Surface settlement monuments should be read by the project surveyor every week for the first 4 weeks, and then every two weeks until measured settlement is within tolerable limits such that additional settlement will not impact site improvements. Based on our experience with similar soil conditions, we estimate 2 to 4 months of monitoring would be necessary to demonstrate that primary consolidation is essentially complete. 7.7 Slope Stability 7.7.1 Slope stability analyses, utilizing average drained direct shear strength parameters, indicate proposed fill slopes constructed with on-site granular materials and cut slopes within formational material should have calculated factors of safety of at least 1.5 under static conditions with respect to both deep-seated failure and shallow sloughing conditions. Results of the analyses are presented on Figures 10 through 14.Additionally,an inclination of 1.5 to 1 (horizontal to vertical) is acceptable for slopes excavated into the Salto Intrusive and Santiago Formation provided no adverse jointing, fractures, or bedding exist.All cut slopes should be observed by a geologist to assess if adverse bedding, jointing, or fractures exist. 7.7.2 There are steep to near vertical cut slopes within the northeast portion of the site.These slopes were excavated during mining operations.The stability of these slopes should be ,r1 evaluated when ultimate grading and use of this area is known. Various options such as lay back, stability fill or soil nailing/rock bolting may be considered at the time. Alternatively, Project No. 07135-42-05 -16 -February 24, 2015 slope set-backs and rock retention fences can be utilized.For preliminary planning purposes, we recommend a set-back for site improvements of 20 feet from the toe of slope in conjunction with the construction of a debris ditch and rock retention fence. Additionally, we recommend loose rock and accumulated soil on the slope face and at the top of the slope be removed. The construction of the debris ditch and rock retention fence should occur during fine grading of the pad once pad usage and improvement locations have been determined. 7.7.3 The proposed 45 feet high cut slope located at the southwest boundary,adjacent to Simsbury Court,will be excavated into Terrace Deposits. Our large diameter boring LB -2 encountered materials consisting of interbedded silty sand,cohessionless sand and clay layers which were occasionally partially remolded. Our analysis indicates that a buttress fill will be required to provide adequate slope stability. Based on our analysis, the stability buttress will need to have a minimum width of 30 feet to provide adequate stability. A typical buttress fill detail is provided in Figure 15.A discussion our stability analysis is presented in Appendix C. 7.7.4 Excavations including buttresses, shear keys, and stability fills should be observed during grading by an engineering geologist to evaluate whether soil and geologic conditions do not differ significantly from those expected.Buttress shear key and associated subdrains should be surveyed during construction and depicted on the final as-built grading plans. 7.7.5 We performed the slope stability analyses based on the interpretation of geologic conditions encountered during our field investigation.In certain areas,the geologic conditions such as the localized or continuous features of the bedding plane shears may need to be further defined by additional field exploration based on our review of the 40-scale grading plans. 7.7.6 The outer 15 feet (or a distance equal to the height of the slope, whichever is less)of fill slopes should be composed of properly compacted granular "soil"fill to reduce the potential for surficial sloughing. 7.7.7 Fill slopes should be overbuilt at least 3 feet and cut back to the design finish grades. Alternatively, fill slopes can be compacted by backrolling with a loaded sheepsfoot roller or tracked walked by sufficiently by a D-8 dozer or equivalent, at vertical intervals not to exceed 4 feet.Slope should be uniformly compacted to a dry density of at least 90 percent of the laboratory maximum dry density to the face of the finished slope. Project No. 07135-42-05 -17 -February 24, 2015 7.7.8 All slopes should be landscaped with drought-tolerant vegetation having variable root depths and requiring minimal landscape irrigation. In addition, all slopes should be drained and properly maintained to reduce erosion.Slope planting should generally consist of drought tolerant plants having a variable root depth.Slope watering should be kept to a minimum to just support the plant growth. 7.8 Seismic Design Criteria 7.8.1 We used the computer program U.S.Seismic Design Maps,provided by the USGS. Table 7.8.1 summarizes site-specific design criteria obtained from the 2013 California Building Code (CBC; Based on the 2012 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 building structures and improvements should be designed using a Site Class C.We evaluated the Site Class based on the discussion in Section 1613.3.2 of the 2013 CBC and Table 20.3-1 of ASCE 7-10. The values presented in Table 7.8.1 are for the risk-targeted maximum considered earthquake (MCER). TABLE 7.8.1 2013 CBC SEISMIC DESIGN PARAMETERS Parameter Value 2013 CBC Reference Site Class D Section 1613.3.2 MCER Ground Motion Spectral Response 1.067g Figure 1613.3.1(1)Acceleration —Class B (short),Ss MCER Ground Motion Spectral Response Acceleration—Class B (1 sec), Si 0.413g Figure 1613.3.1(2) Site Coefficient,FA 1.073 Table 1613.3.3(1) Site Coefficient, Fv 1.587 Table 1613.3.3(2) Site Class Modified MCER 1.145g Section 1613.3.3 (Eqn 16-37)Spectral Response Acceleration (short),SNIS Site Class Modified MCER 0.656g Section 1613.3.3 (Eqn 16-38)Spectral Response Acceleration (1 sec),S511 5% Damped Design 0.763g Section 1613.3.4 (Eqn 16-39)Spectral Response Acceleration (short),SDS 5% Damped Design 0.437g Section 1613.3.4 (Eqn 16-40)Spectral Response Acceleration (I 7.8.2 Table 7.8.2 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). Project No. 07135-42-05 -18 -February 24, 2015 TABLE 7.8.2 2013 CBC SEISMIC DESIGN PARAMETERS Parameter Value ASCE 7-10 Reference Mapped MCEG Peak Ground Acceleration, PGA 0.407g Figure 22-7 Site Coefficient,FPGA 1.093 Table 11.8-1 Site Class Modified MCEG 0.445g Section 11.8.3 (Eqn 11.8-1)Peak Ground Acceleration, PGAM 7.8.3 Conformance to the criteria in Tables 7.8.1 and 7.8.2 for seismic design does not constitute any kind of guarantee or assurance that significant structural damage or ground failure will not occur if a large earthquake occurs. The primary goal of seismic design is to protect life, not to avoid all damage, since such design may be economically prohibitive. 7.9 Foundation and Concrete Slab-On-Grade Recommendations 7.9.1 The foundation recommendations that follow are for one-to three-story residential structures and are separated into categories dependent on the thickness and geometry of the underlying fill soils as well as the expansion index of the prevailing subgrade soils of a particular building pad (or lot). Categories for each building pad or lot will be provided after the completion of grading once fill thickness is known and expansion index testing has been performed on finish grade soils. TABLE 7.9.1 FOUNDATION CATEGORY CRITERIA Foundation Maximum Fill Differential Fill Expansion Category Thickness, T (feet)Thickness, D (feet)Index (El) I T<20 EI<50 II 20<T<50 1O<D<20 50<El<90 III T>50 D>20 90<EI<130 7.9.2 Table 7.9.2 presents minimum foundation and interior concrete slab design criteria for conventional foundation systems. Project No. 07135-42-05 -19 -February 24, 2015 TABLE 7.9.2 CONVENTIONAL FOUNDATION RECOMMENDATIONS BY CATEGORY Minimum FootingFoundation Continuous Footing Interior SlabEmbedment DepthCategory Reinforcement Reinforcement(inches) 12 Two No. 4 bars,6x6-10/10 welded wire one top and one bottom mesh at slab mid-point II 18 Four No. 4 bars,No.3 bars at 24 inches two top and two bottom on center, both directions III 24 Four No.5 bars,No.3 bars at 18 inches two top and two bottom on center, both directions 7.9.3 The embedment depths presented in Table 7.9.2 should be measured from the lowest adjacent pad grade for both interior and exterior footings. The conventional foundations should have a minimum width of 12 inches and 24 inches for continuous and isolated footings, respectively. 7.9.4 The concrete slab-on-grade should be a minimum of 4 inches thick for Foundation Categories I and II and 5 inches thick for Foundation Category III. 7.9.5 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 (ACI) Guide for Concrete Slabs that Receive Moisture-Sensitive Flooring Materials (ACI 302.2R-06). In addition,the membrane should be installed in accordance with manufacturer's recommendations and ASTM requirements,and in a manner that prevents puncture.The project architect or developer should specify the vapor retarder based on the type of floor covering that will be installed and if the structure will possess a humidity controlled environment. 7.9.6 The project foundation engineer,architect,and/or developer should determine the thickness of bedding sand below the slab.In general,3 to 4 inches of sand bedding is typically used.Cieocon should be contacted to provide recommendations if the bedding sand is thicker than 6 inches. 7.9.7 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 specify the concrete mix design and proper curing methods on the foundation plan. It Project No. 07135-42-05 -20 -February 24, 2015 is critical that the foundation contractor understands and follows the recommendations presented on the foundation plan. 7.9.8 As an alternative to the conventional foundation recommendations, consideration should be given to the use ofpost-tensioned concrete slab and foundation systems for the support of the proposed structures. The 2013 CBC has updated the design requirements for post-tensioned foundation systems. 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), Third Edition,as required by the 2013 CBC (Section 1805.8). 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 geotechnical parameters presented in Table 7.9.3 for the particular Foundation Category designated. The parameters presented in Table 7.9.3 are based on the guidelines presented in the PTI, Third Edition design manual. TABLE 7.9.3 POST-TENSIONED FOUNDATION SYSTEM DESIGN PARAMETERS Post-Tensioning Institute (PTI)Foundation Category Third Edition Design Parameters I II III Thornthwaite Index -20 -20 -20 Equilibrium Suction 3.9 3.9 3.9 Edge Lift Moisture Variation Distance,em (feet)5.3 5.1 4.9 Edge Lift,ym (inches)0.61 1.10 1.58 Center Lift Moisture Variation Distance,em (feet)9.0 9.0 9.0 Center Lift,ym (inches)0.30 0.47 0.66 7.9.9 If the structural engineer proposes a post-tensioned foundation design method other than the 2013 CBC: •The criteria presented in Table 7.9.3 are still applicable. •Interior stiffener beams should be used for Foundation Categories 11 and Ill. •The width of the perimeter foundations should be at least 12 inches. •The perimeter footing embedment depths should be at least 12 inches,18 inches and 24 inches for foundation categories 1,II,and III, respectively. The embedment depths should be measured from the lowest adjacent pad grade. Project No. 07135 -42-05 -21 -February 24, 2015 7.9.10 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 at least 6 inches below the clean sand or crushed rock layer. 7.9.11 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 PTI 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. 7.9.12 During the construction of the post-tension foundation system,the concrete should be placed monolithically.Under no circumstances should cold joints form between the footings/grade beams and the slab during the construction of the post-tension foundation system. 7.9.13 Category I, II, or III foundations may be designed for an allowable soil bearing pressure of 2,000 pounds per square foot (psf)(dead plus live load).This bearing pressure may be increased by one-third for transient loads due to wind or seismic forces.The estimated maximum total and differential settlement for the planned structures due to foundation loads is 1 -inch and 1/2-inch, respectively. Differential settlement is estimated to occur over a span of 40 feet. 7.9.14 We expect primary settlement of existing fills is essentially complete.However,we estimate that additional settlement as a result of hydro-consolidation to be approximately 0.2 to 0.3 percent of the total fill thickness. We expect hydro-consolidation to occur over a 20 year or more duration.We estimate a total fill settlement as a result of hydro- consolidation to be 1 -inch or less in areas where compacted fill exists.A more refined estimate of total and differential fill thickness can he made once buildin.locations on individual sheet graded pads 7.9.15 Foundations will need to be designed to accommodate estimated total and differential fill settlement from both building loading and hydroconsolidation.In addition, building pads on Lot 2 where alluvium was left in-place should incorporate the estimated liquefaction settlement. Project No. 07135-42-05 -22 -February 24, 2015 7.9.16 Isolated footings, including PT foundation systems where footings are not reinforced with PT cables,should have the minimum embedment depth and width recommended for conventional foundations (see Section 7.9.1 through 7.9.3)for a particular foundation category.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 for Category III. Where this condition cannot be avoided, the isolated footings should be connected to the building foundation system with grade beams. 7.9.17 For Foundation Category III,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 five feet in width, to the building foundation to reduce the potential for future separation to occur. 7.9.18 Special subgrade presaturation is not deemed necessary prior to placing concrete; however, the exposed foundation-and slab-subgrade soil should be moisture conditioned,as necessary,to maintain a moist condition as would be appropriate in any such concrete placement. 7.9.19 Where buildings or other improvements are planned near the top of a slope steeper than 3:1 (horizontal:vertical),special foundations and/or design considerations are recommended due to the tendency for lateral soil movement to occur. •For fill slopes less than 20 feet high or cut slopes regardless of height,footings should be deepened such that the bottom outside edge of the footing is at least 7 feet horizontally from the face of the slope. •For fill slopes greater than 20 feet high, foundations should be extended to a depth where the minimum horizontal distance is equal to II/3 (where H equals the vertical distance from the top of the fill slope to the base of the fill soil) with a minimum of 7 feet but need not exceed 40 feet.The horizontal distance is measured from die outer, deepest edge of the footing to the face of the slope.A post-tensioned slab and foundation system or mat foundation system can be used to help reduce potential foundation distress associated with slope creep and lateral fill extension.Specific design parameters or recommendations for either of these alternatives can be provided once the building location and fill slope gconietry have been determine 1. •If swimming pools are planned,Geocon Incorporated should be contacted for a review of specific site conditions. •Swimming pools located within 7 feet of the top of cut or fill slopes are not recommended.Where such a condition cannot be avoided,the portion of the swimming pool wall within 7 feet of the slope face be designed assuming that the Project No. 07135-42-05 -23 -February 24, 2015 adjacent soil provides no lateral support.This recommendation applies to fill slopes up to 30 feet in height, and cut slopes regardless of height. For swimming pools located near the top of fill slopes greater than 30 feet in height, additional recommendations may be required and Geocon Incorporated should be contacted for a review of specific site conditions. •Although other improvements that are relatively rigid or brittle,such as concrete flatwork or masonry walls, may experience some distress if located near the top of a slope,it is generally not economical to mitigate this potential. It may be possible, however,to incorporate design measures that would permit some lateral soil movement without causing extensive distress.Geocon Incorporated should be consulted for specific recommendations. 7.9.20 The exterior flatwork recommendations provided herein assumes that the near surface soils are very low to low expansive (EI <50). Exterior slabs not subjected to vehicular traffic should be a minimum of four inches thick and reinforced with 6 x 6-6/6 welded wire mesh. The mesh should be placed in the middle 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 upper 12 inches of subgrade soils should be moisture conditioned at or slightly above optimum moisture content and compacted to at least 90 percent ofthe laboratory maximum dry density per ASTM 1557. 7.9.21 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.The occurrence may be reduced and/or controlled by:(1) limiting the slump of the concrete, (2) proper concrete placement and curing, and by (3) the placement of crack control joints at periodic intervals, in particular, where re-entrant slab corners occur. 7.9.22 Geocon Incorporated should be consulted to provide additional design parameters as required by the structural engineer. 7.10 Retaining Wall Recommendations 7.10.1 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 Project No. 07135-42-05 -24 -February 24, 2015 soil pressure of 50 pcf is recommended.Expansive soils should not be used as backfill material behind retaining walls.All soil placed for retaining wall backfill should have an Expansion Index less than 50. 7.10.2 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. 7.10.3 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. 7.10.4 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 wall possesses a height of 8 feet or less and 12H where the wall is greater than 8 feet. 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 (unit weight 130 pcf). 7.10.5 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 of less than 50)free-draining. backfill material with no hydrostatic forces or imposed surcharge load.Fipiire 16 presents a typical drainage detail.II conditions different than those described are expected,or if specific drainage details are desired, Geoco Incorporated should be contacted for additional recommendations. •7.10.6 The structural engineer should determine the seismic design category for the project in accordance with Section 1613 of the CBC.If the project possesses a seismic design Project No. 07135-42-05 -25 -February 24, 2015 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 18.3.5.12 of the 2013 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 21H should be used for design.We used the peak ground acceleration adjusted for Site Class effects,PGAM.of 0.445g calculated from ASCE 7-10 Section 11.8.3 and applied a pseudo-static coefficient of0.33. 7.10.7 In general,wall foundations having a minimum depth and width of one foot may be designed for an allowable soil bearing pressure of 2,000 psf, provided the soil within 3 feet below the base of the wall consists of compacted fill with an Expansion Index of less than 90. The allowable soil bearing pressure can be increased by 300 psf and 500 psf for each additional foot of foundation width and depth,respectively,up to a maximum allowable soil bearing 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 anticipated. 7.10.8 Resistance to lateral loads will be provided by friction along the base of the wall foundation or by passive earth pressure against the side of the footing.Allowable coefficients of friction of 0.35 are recommended for footings in compacted fill.Passive earth pressure may be taken as 150 pcf for walls founded on a 2:1 slope, and 300 pcf for horizontal ground in front of the wall. The allowable 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. 7.10.9 The recommendations presented above are generally applicable to the design of rigid concrete or masonry retaining walls having :1 maximum height of s feet.In the event that walls higher than 8 feet are planned,Geocon Incorporated should be consulted fur additional recommendations. 11 Dot....ntion 'Basin and 9losvglh 7)commIndations 7.11.1 Any detention basins,bioswales and bio-remediation areas should be designed by the project civil engineer and reviewed by Geocon Incorporated. Typically, bioswales consist of a surface layer of vegetation underlain by clean sand.A subdrain should be provided beneath the sand layer. Prior to discharging into the storm drain pipe,a seepage cutoff wall should be constructed at the interface between the subdrain and storm drain pipe.The Project No. 07135-42-05 -26 -February 24, 2015 concrete cut-off wall should extend at least 6-inches beyond the perimeter of the gravel- packed subdrain system. 7.11.2 Distress may be caused to planned improvements and properties located hydrologically downstream or adjacent to these devices. The distress depends on the amount of water to be detained,its residence time,soil permeability,and other factors.We have not performed a hydrogeology study at the site. Downstream and adjacent properties may be subjected to seeps, springs, slope instability, raised groundwater, movement of foundations and slabs, or other impacts as a result of water infiltration. Due to site soil and geologic conditions,permanent bioswales and bio-remediation areas should be lined with an impermeable barrier,such as a thick visqueen,to prevent water infiltration in to the underlying compacted fill. 7.11.3 The landscape architect should be consulted to provide the appropriate plant recommendations.If drought resistant plants are not used, irrigation may be required. 7.12 Site Drainage and Moisture Protection 7.12.1 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 2013 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 structure. 7.12.2 In the case of basement walls or building walls retaining landscaping areas,a water- proofing system should be used on the Nvall 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. 7.12.3 Underground utilities should be leak free.Utility and irrigation lines should he 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. 7.12.4 Adequate drainage provisions are imperative.Under no circumstances should water be allowed to pond adjacent to footings. The building pads should be properly finish graded after the buildings and other improvements are in place so that drainage water is directed Project No. 07135 -42-05 -27 -February 24, 2015 away from foundations, pavements, concrete slabs, and slope tops to controlled drainage devices. Project No. 07135-42-05 -28 -February 24, 2015 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 ofthe 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.change;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. 07135 -42-05 February 24, 2015