"Final Embankment Rept:Main Dam."
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CAROLINA POWER & LIGHT COMPANY SHEARON HARRIS NUCLEAR POWER PLANT FINALEMBANKMENTREPORT MAIN DAM . 7 Dockside S<-V~o Conti g. el 83o38oc WV'f Document KGUQTO DOCKH FlLE L EBASCO SERVICES INCORPORATED Two World Trade Center New York, N.Y. NOVEMBER 1981 8308300292 830824 PDR ADOCK 05000400 A PDR CAROLINA PONFR 8 LIGHT COMPANY SHEARON HARRIS NUCLEAR POWER PLANT o a MAIIM DAM EBASCO SERVICES INCORPORATED Two World Trade Center New York, N.Y. NOVEMBER 1981 TABLE OF CONTENTS ' Page Summary and Conclusions II. Introduction 4 III. Project Description IV. Foundation Conditions V. Construction History A. General 4 B. Reservoir Clearing C. Diversion Works 10 D. Foundation Excavation and Preparation E. Borrow Area Investigations 12 F,. Placement of Impervious Core and Filter Materials 13 G. Placement of Rockfill and Riprap 13 H. Reservoir Filling 14 VI. Material Sources 16 A. Preconstruction Investigations 16 B. Impervious Core Materials 16 . C. Filters and Bedding 17 D. Rockfill and Riprap 18 VII. Embankment Construction Control 19 A. Introduction 19 B, Description of Inspection Procedures 20 B.l. General 20 B.2. Testing Frequencies 20 B.3. Pemedial Measures 21 C. Lmpervious Core Materials 21 C.l. Technical Requirements 21 C.2. Moisture Control and Placement Technique 23 C.3, Field Testing Procedures 25 C.'4. Summary of Field Testing 'Results 28 C.5. Special Problems 30 D. Filter Materials and Crushed Rock Backfill 31 D.l. Technical Requirements 31 D.2. Placement Technique D.3. Field Testing Procedures 34 D.4. Relative Density Control of Filter 35 Materials D.5. Summary of Field Testing Results 37 D.6. Special Problems 39 E, Rockfill 40 H.l. Technical Requirements 40 E.2. Placement Technique 42 E.3. Field Testing Procedures 42 E.4. Triaxial Shear Testing Results 43 E.5. Summary of Field Testing Results 44 E.6. Special Problems 'F. Riprap and Riprap Bedding 45 F.l. Technical Requirements 45 F.2. Placement Technique 47 F.3. Field Testing Procedures 47 F.4. Summary of Field Testing Results 48 F.5 ~ Special Problems 49 G. Summary and Evaluation of Testing Results 49 4f G.l. Impervious Core Materials 49 G.2. Filter Materials and Crushed Rock Backfill 50 G.3. Rockfill 50 G.4. Riprap and Riprap Bedding 51 G.5. General 51 VIII. Instrumentation 53 A. Piezometers and Seepage Monitors 53 B. Settlement Monumetns References TABLES Test Standards Testing Frequency Guidelines Specified Gradation of Impervious Fills Summary of Material Lift Thicknesses and'ompaction Equipment Placement Quantities by Month Density Testing Frequencies by Month Specified Gradation of Filters and Bedding Summary of Maximum and Minimum Density Values for Main Dam Test Sections Specified Gradation of Rockfill Variation of Rockfill Density, Permeability and Strength FIGURES Location Map — Main Dam '2. Main Dam — General Plan 3. Main Dam — Profile and Typical Section (Sheets,l-5) 4. Main Dam Spillway — Plan and Profile 5. Hain Dam Spillway Sections 6. Construction Sequence and Schedule (Sheets 1-2) 7. Rainfall versus Time — 1979-1980 (Sheets 1-2) 8. Temperature by Day — 1979-1980 (Sheets 1-2) 9. Main Dam Borrow Area M — Construction Investigations 10. Main Dam Borrow Area W Main Dam Quarry Investigation — Location of Borings 'ain Dam Quarry — Plan and Sections Correlation Curve of Rapid Moisture Measuring Device (Typical) 14. Placement Limits of Borrow Area W and Z Impervious 15. Plasticity Chart 16. Grain Size Distribution — Impervious 17. Summary of Standard Proctor Curves — Borrow Area Z 18. Summary of Standard Proctor Curves — Borrow Area W (Sheets 1-3) 19. Density Test Locations and Results — Impervious (Sheets 1-2) 20. Variation of Percentage Compaction and Fill Moisture — Impervious (Sheets 1-3) 21. Correlation of Gradation versus Maximum/Minimum Density — Crushed Rock Backfill 22. Grain Size Distribution — Fine Filter 23. Gxain Size Distribution — Transition Filter Grain Size Distribut'ion — Coarse Filter 25. ('rain Size.e l)istributionl). — Crushed Rock Backfill 26. Density Test Locations and Results — Fine Filter 27. Densit y Test Locations and Results — Transition Filter 28. Density Test Locations and Results — Coarse Filter 29. Density Test Locations and Results—esu ts — Crushed Rock Backfill and Rockfill 30. Variation of Relative Density — Fine Filter 31. Variation of Relative Density — Transition Filter 32. Variation of RelativeRe Density — Coarse Filter (Sheets 1-2) 33. Variation of RelativeR Density — Crushed Rock Backfill 34. Grain Size Distribution — Rockfill 35. Grain Size Distribution — Type A Bedding 36. Reservoir, ,, MainMa Dam Area — Instrumentation APPENDICES A. Photographs Photo 1: Hand Compaction of Impervious Core Materials West of Diversion Conduit Photo 2: Foundation Surface East of Diversion Conduit, Grouting in Progress Photo 3: Foundation Surface East of Diversion Conduit, Dental Concrete Complete Photo 4: Blending of Borrow Area W Photo 5: Close-up of Fill Surface East of Diversion Conduit Photo 6: Trimmed Edge of Impervious Core Photo 7: Overall View of Fill Surface Showing Placement of Fine and Coarse Filters Photo 8: Fill Surface at Elev 178 ft Showing Various Embankment Zones Photo 9: Fill Surface at Elev 178 ft Showing Crushed Rock Backfill Photo 10: Fill Surface at Elev 220 ft Photo ll; Closeup of Fill Surface at Elev 220 ft Photo 12: Cut Slope in Rockfill Quarry Photo 13: I'ill Surface at End of 1980 Construction Season Photo 14: Fill Surface at End of 1980 Construction Season Showing Type A Riprap Laboratory Data —.Alternate Borrow Investigations C. Boring Logs — Quarry Borings QC-1 through QC-9 D. Summary Sheets of Field Compaction Control 4 Table A. Impervious Core Materials Table B. Pine Filter Table C. Transition Filter 'I'able I). Coarse Filter Table E. Crushed Rock Backfill Table F. Rockfill Table G. Riprap Bedding E. Tabulation of Random PX Determinations F. Report — Large Scale Triaxial Shear and Gradation Tests on Rockfill from the Main Dam, Corps of Engineers, December 10, 1980 G. Report — Laboratory Testing of Type A Riprap, Law Engineering Testing Company, May 13, 1980 0 I. SUMMARYAND CONCLUSIONS SlRQfARY AND CONCLUSIONS 0 The Shearon Harris Main Dam is located on Buckhorn Creek approximately 4.5 0 ml'l«s so«th of the Shcnron llnrris Nuclear power plant site and about 2.5 miles north of the Cape Fear River. This report presents a detailed geo- 0 technical documentation of Main Dam embankment construction during .the 1979 and 1980 work seasons. A detailed presentation of foundation excavation, grouting, and geologic mapping has been included in the "Final Geologic Report on Foundation Conditions, Power Plant, Dams, and Related Structures". The Main Dam is an earth and rockfill dam approximately 1550 Eeet long at the crest elevation of 260 feet. The dam is founded on rock and has a maximum height of 108 feet. It has a clay core of compacted impervious fill protected on each side by two eight-ft-thick filter zones and a rockfill shell. Outside slopes are two horizontal to one vertical. The Main Dam impounds a reservoir with a normal water level at El 220 ft and a water surface area of approximately 4000 acres. Clearing for the Main Dam began in early 1978. Excavation of the Stage I diversion channel and diversion of Buckhorn Creek was completed in June 1978. Excavation of the core trench and rockfill shell foundation areas lit began in mid-1978. Construction of the diversion conduits also began in mid- 1978. The diversion conduits and Stage II cofferdams were. completed in April 1979, allowing diversion of Buckhorn Creek from the channel to the conduit. Foundation preparation including clean-up, geologic mapping, placement of 'I dental concrete, and consolidation and curtain grouting continued intermittently July 1979 and continued until late December 1979, when embankment construction wns suspended because of bad weather conditions. Placements resumed in Apri1 1980 and continued without interruption until December 1980. At the end of the 1980 construction season approximately 98% of embankment fi'lls had been placed. The embankment construction control program consisted of field and laboratory inspection and testing of all impervious fill, filter materials, rockfill, bedding, and riprap placed in the embankment. Tests were performed to verify that soil properties and placement density and moisture met specification requirements. Field and laboratory testing were performed in accordance with ASTM Standards as required by Ebasco Specifications. Impervious core materials, filters and rockfill have been placed and compacted as summarized below. Impervious soils were placed at a mean compactive effort of 101% Standard Proctor. The mean difference between fillmoisture and Standard Proctor optimum moisture was -0.2% in those areas required to be placed at optimum moisture (+2%) and +1.2% in those areas required to be placed at 0 to +4% above optimum moisture. Fine filter was placed at a mean relative density of 80%. Coarse filter was placed at a mean relative density of 83%. Coarse filter placed on the upstream side of the dam above Elevation 220 ft was 9 compacted to a mean relative density of 84%. Transition filter was placed at a mean relative density of 82%. Crushed rock backfill was placed at a mean relative density of 93%. Rockfill was placed at an average inplace dry density of 142 pcf. All measurements of inplace rockfill permeability indicated values V in excess'of 10 cm/sec. Two largb diameteQ triaxial strength tests were performed 0 ~ ~ on Main Dam rockfill. 'An effective friction angle (I') of 44.5 was measured in o each test. Placements "of riprap and riprap bedding met design requirements in aspects. All aspects of the earthwork quality control program conformed with accepted practice for large earth and rockfill dams. Field inspection and laboratory testing procedures were adequate to ensure that the earth- work was constructed according to the designer's intent. With minor exceptions, materials placed in the 1979-1980 construction seasons met E specification and design requirements in all aspects.