Student: Stanley


APPENDIX C GEOTECHNICAL EVALUATION ESCONDIDO PURE WATER PIPELINE CREEK CROSSING MARCH 20, 2019 Prepared for: The City of Escondido Prepared By: Donovan & Associates 5500 Campanile Drive San Diego, CA 92182 Table of Contents 3.1 Introduction 3.2 Background 3.3 Purpose and Objective 3.4 Subsurface Conditions 3.5 Geologic Hazards 3.6 Recommendations 3.7 Conclusions 3.8 References 3.9 Attachments   3.1 Introduction This geotechnical report was prepared to provide information, recommendations, and guidance for the proposed Escondido Pure Water Pipeline Creek Crossing located near the intersection of Washington and Spruce Street in Escondido, California. This report utilized soils data obtained by bore logs and laboratory testing provided by Ninyo and Moore in order to evaluate subsurface conditions, seismic conditions, and potential design recommendations for any subsurface structures or construction which may be necessary at the project site. 3.2 Background Two methods of crossing the creek were provided in client request for proposal. One option was to bore underneath the crossing as to not disturb the creek or channel structure. The other option was to construct a structure which could span over the creek and carry the proposed pipeline over. Both methods require work within the subsurface layers of the site and require geotechnical evaluation and guidance to ensure there are no damages to the pipeline, creek, environment, structures, or persons. 3.3 Purpose and Objective This geotechnical report serves to recompile, analyze, and make recommendations upon soils data that was provided to Donovan and Associates from a previous soils investigation that occurred at the project site. The soils data was provided by Ninyo and Moore, and hence, exploratory boring was not included in the scope of work for this geotechnical evaluation. The work and services provided by Donovan and Associates for this report: 1. Compile a soil profile with various layers for soil pressure evaluation at various depths. 2. Compile references to include geological maps, fault maps, codes, jurisdictional guidelines, and other geologic reports that are relevant to the project location. 3. Analyze references and provided data to create proper descriptions of site characteristics. 4. Calculate necessary parameters for design recommendations such as soil pressures, bearing capacities, settlement, and dimensioning for subsurface structures. 5. Provide design and construction recommendations based on combination of calculations and references. 3.4 Subsurface Conditions Boring Log No. 3, which was provided by Ninyo and Moore, was located directly at the proposed project site. Samples collected from the exploratory boring indicate two types of soil layers: Alluvium and Granite Rock. The alluvium at the site consists of a sublayer of silty fine sand, over a layer of fine to medium sand, followed by a layer of dense, well graded sand. The alluvium deposits were found 6’ under artificial fill and deepened to about 32’ where granite rock was discovered. The exploratory boring continued to a depth of 50’, but no other layer was present aside from the granite rock. The soil at this location is described as “Class-D” type stiff soil. Groundwater was encountered at approximately 17’ depth. However, the site is located within an alluvial basin the groundwater level is subject to seasonal changes due to changes in rainfall, irrigation, and replenishment. Soil materials located below the groundwater location are denser due to the voids within the material being filled with water. Groundwater in Escondido flows from north to south and east to west (USGS, 1989). 3.5 Geologic Hazards There are no active faults in Escondido that are reported by the Alquist-Priolo Earthquake Fault Zone application. However, faults outside of Escondido still pose a seismological hazard to the site through ground motion. Segments of the San Jacinto, Elsinore, and Rose Canyon fault zones are capable of affecting sites within the county of San Diego, but do not pose a significant risk of ground rupture. There are no poorly graded loose sands located in the subsurface layers of the site. Thus, liquefaction due to seismic events is not probable, however the Escondido City General Plan places the project site within an area for liquefaction hazard. It is possible that high saturation due to a high water table may lead to lateral spread and uplift. Special care will be taken care to ensure that any structures or construction are not threatened. 3.6 Recommendations *Upon completion of preliminary evaluation and selection of crossing method, recommendations will be compiled and provided in a final report.* 3.7 Conclusions *Final Conclusions will be provided for the method of conveyance agreed upon by Donovan and Associates and the Client in the final draft of this report.* 3.8 References References for Geotech: References cited list - USGS?NGA? Valdez notebook? Any geotech textbooks? Is this where MArcs provided data/report would go? Guidelines for Geotechnical Report, City of San Diego 2018 US Dept. Ag Soil Conservation Service and Forest Service Soil Survey (Page 45 for Escondido Information) Department of Conservation Geologic Hazards Map ) California Geological Survey Fault Maps and Earthquake Zones USGS Quaternary Faults Map Seismic Maps (includes Design Values) EarthQuake Authority Principles of Geology, Third Edition, Gilluly Water and Woodford Book San Diego County Geologic Hazards Guidelines FEMA Floodmaps Escondido General Plan (Floor and Seismic Hazards) (Page 14 Flood, Page 18 Seismic) USGS Geohydrology of Escondido MFRO Geotechnical Evaluation (PROVIDED BY MARK??) 3.9 Attachments

Budget: $7.00

Due on: May 03, 2020 00:00

Posted: 11 months ago.

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