GEOTECHNICAL ENGINEERING STUDY FOR LAKE LAKEWOOD PARK SITE LEANDER, TEXAS Project No. AAA17‐091‐00 Raba Kistner Original Submission February 02, 2018 Consultants, Inc. 8100 Cameron Road, Suite B-150 Revised, February 23, 2018 Austin, TX 78754 www.rkci.com Mr. Dan Franz, P.E., CFM P 512 :: 339 :: 1745 Halff Associates, Inc. F 512 :: 339 :: 6174 9500 Amberglen Boulevard, Building F, Suite 125 TBPE Firm F-3257 Austin, Texas 78729 RE: Geotechnical Engineering Study Lake Lakewood Park Site Leander, Texas Dear Mr. Franz: RABA KISTNER Consultants Inc. (RKCI) is pleased to submit the report of our Geotechnical Engineering Study for the above‐referenced project. This study was performed in accordance with RKCI Proposal No. PAA17‐178‐00, dated November 13, 2017. The purpose of this study was to drill 9 borings, to perform laboratory testing to classify and characterize subsurface conditions, and to prepare an engineering report presenting foundation design and construction recommendations for the proposed Lake Lakewood Park, as well as to provide pavement design and construction guidelines. This report has been revised to address concerns associated with foundation and pavements being constructed within the flood plain. The following report contains our design recommendations and considerations based on our current understanding of information provided to us at the time of this study. There may be alternatives for value engineering of the foundation and pavement systems. RKCI recommends that a meeting be held with the Owner and design team to evaluate if alternatives are available. We appreciate the opportunity to be of service to you on this project. Should you have any questions about the information presented in this report, or if we may be of additional assistance with value engineering or on the materials testing‐quality control program during construction, please call. Very truly yours, RABA KISTNER CONSULTANTS, INC. Richard T. Shimono, E.I.T. Yvonne Garcia Thomas, P.E. 02/23/2018 Graduate Engineer Associate RTS/YGT: tlc Attachments Copies Submitted: Above (1‐electronic) O:\Closed Projects\Austin\2017\AAA17-091-00 Lake Lakewood Park Site\Reporting\AAA17-091-00 Lake Lakewood 2 22 2018 FINAL.docx GEO100 04/09/2014 San Antonio • Austin • Brownsville • Dallas • Houston • McAllen • Mexico • New Braunfels • Salt Lake City GEOTECHNICAL ENGINEERING STUDY For LAKE LAKEWOOD PARK SITE LEANDER, TEXAS Prepared for HALFF ASSOCIATES, INC. Austin, Texas Prepared by RABA KISTNER CONSULTANTS, INC. Austin, Texas PROJECT NO. AAA17‐091‐00 Revised, February 23, 2018 Project No. AAA17‐091‐00 i Revised, February 23, 2018 TABLE OF CONTENTS INTRODUCTION .......................................................................................................................................... 1 PROJECT DESCRIPTION ............................................................................................................................... 1 LIMITATIONS .............................................................................................................................................. 1 BORINGS AND LABORATORY TESTS ........................................................................................................... 2 GENERAL SITE CONDITIONS ....................................................................................................................... 3 SITE DESCRIPTION ......................................................................................................................................... 3 GEOLOGY ....................................................................................................................................................... 3 SEISMIC CONSIDERATIONS ........................................................................................................................... 3 STRATIGRAPHY .............................................................................................................................................. 4 GROUNDWATER ............................................................................................................................................ 4 FOUNDATION ANALYSIS ............................................................................................................................. 4 EXPANSIVE SOIL‐RELATED MOVEMENTS ..................................................................................................... 4 OVEREXCAVATION AND SELECT FILL REPLACEMENT .................................................................................. 5 DRAINAGE CONSIDERATIONS ....................................................................................................................... 5 FOUNDATION RECOMMENDATIONS .......................................................................................................... 6 FOUNDATION CONSIDERATIONS .................................................................................................................. 6 FOUNDATION OPTIONS ................................................................................................................................ 7 Restrooms, Pavilions, Boat/Rental Facility ............................................................................................ 7 Fishing Pier/Boardwalk........................................................................................................................... 7 SITE GRADING ................................................................................................................................................ 7 SPECIAL CONSIDERATIONS ‐ FOUNDATIONS ............................................................................................... 7 ENGINEERED BEAM AND SLAB FOUNDATION ............................................................................................. 8 Allowable Bearing Capacity .................................................................................................................... 8 B.R.A.B. Criteria ...................................................................................................................................... 8 PTI Design Parameters ........................................................................................................................... 9 SHALLOW SPREAD FOOTING FOUNDATIONS ............................................................................................ 10 Allowable Bearing Capacity .................................................................................................................. 10 AREA FLATWORK ......................................................................................................................................... 11 DRILLED, STRAIGHT‐SHAFT PIERS ............................................................................................................... 11 Pier Shaft Potential Uplift Forces ......................................................................................................... 12 Allowable Uplift Resistance .................................................................................................................. 12 PIER SPACING .............................................................................................................................................. 12 RETAINING STRUCTURES .......................................................................................................................... 13 LATERAL EARTH PRESSURES ....................................................................................................................... 13 BACKFILL COMPACTION .............................................................................................................................. 14 DRAINAGE .................................................................................................................................................... 14 Project No. AAA17‐091‐00 ii Revised, February 23, 2018 TABLE OF CONTENTS RETAINING WALL FOOTINGS ...................................................................................................................... 14 SPECIAL CONSIDERATIONS – RETAINING WALLS ....................................................................................... 15 FOUNDATION CONSTRUCTION CONSIDERATIONS ................................................................................... 15 SITE DRAINAGE ............................................................................................................................................ 15 SITE PREPARATION ...................................................................................................................................... 16 SELECT FILL .................................................................................................................................................. 16 CLAY CAP ...................................................................................................................................................... 17 SHALLOW FOUNDATION EXCAVATIONS .................................................................................................... 17 DRILLED PIERS .............................................................................................................................................. 18 Reinforcement and Concrete Placement ............................................................................................ 18 Casing ...................................................................................................................................................