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ADDENDUM 4 - 7460 - 19829G - US Highway 380 Waterline Geotechnical Report The seal appearing on this document was authorized by James F. Phipps, P.E. 84778 on May 2, 2019. geotechnical and construction materials consultants May 2, 2019 Report No. 19829G Birkhoff, Hendricks & Carter, LLP 11910 Greenville Avenue, Suite 600 Dallas, Texas 75243 ATTN: Mr. Cooper E. Reinbold, E.I.T. Phone: 214-361-7900 Email: creinbold@bhcllp.com RE: Geotechnical Investigation US Highway 380 Waterline US Highway 380 and I-35 Denton, Texas Mr. Reinbold: Presented herein is the report of a limited geotechnical investigation conducted by Henley-Johnston & Associates, Inc. for the above referenced project. We appreciate the opportunity to provide this report to you. If we can be of further service or if you desire any additional information, please do not hesitate to call. Signed, HENLEY-JOHNSTON & Associates, Inc. Benjamin Clarke, E.I.T. James F. Phipps, P.E. Project Manager Vice President Firm Registration No.: F-1238 Copies submitted (2) Birkhoff, Hendricks & Carter, LLP – Mr. Cooper E. Reinbold, E.I.T., Mr. Gary Hendricks, P.E. Report No. 19829G May 2, 2019 - 1 - INVESTIGATION AND ANALYSIS Introduction This report presents the results of a limited subsurface investigation performed for proposed 16- and 20-inch water lines along US Highway 380 and Interstate 35 in Denton, Texas. The purpose of this investigation was to provide information on the anticipated types of materials to be encountered during installation of the lines and earthwork criteria for backfill of the utility trench. This report is specific to this site. Persons using the recommendations herein for projects and/or designs not covered by this report do so at their own risk. Field and Laboratory Investigation Based on the size and layout of the project, subsurface conditions were evaluated with a total of four soil borings. Two of the borings were located along the west side of Interstate 35 just south of US Highway 30, while the remaining borings were located along the east side of Interstate 35 just south of US Highway 380. Locations of the borings were dictated by the client and site accessibility and are presented on Plate 1. Borings were drilled using a truck-mounted rig equipped with continuous flight augers and extended to depths of 15 to 20 feet below existing (April 2019) grades. Drilling and sampling were done in general accordance with ASTM methods and standards. Relatively undisturbed samples of cohesive soil and weathered shale were obtained with three-inch diameter thick-walled Shelby tubes. Weathered and unweathered limestone and unweathered shale were evaluated using the TxDOT Cone Penetration Test (CPT). Clayey sands and unweathered shale were sampled and evaluated in-situ using Standard Penetration Test (SPT) [ASTM 1586]. All samples were transported to the Henley-Johnston & Associates, Inc. (HJA) laboratory for visual classification and testing. Soils were visually classified according to the Unified Soil Classification System (USCS). Rock materials were described using standard geological nomenclature. The Boring Logs and a key to terms and symbols used on the logs are attached. Selected samples were tested to confirm visual classification. Tests conducted included Atterberg Limits (ASTM D-4318) and moisture content determinations (ASTM D-2216). The strength properties of selected samples were investigated by the Unconfined Compression test (ASTM D-2166). Results of these laboratory tests are presented on Plates 2 and 3. Surface and Subsurface Conditions Surface Conditions At the time of the field investigation, the majority of the proposed alignment for the water lines was being used for commercial purposes. Report No. 19829G May 2, 2019 - 2 - Geologic Setting Review of geologic maps indicates the proposed alignment appears to be within the Lower Cretaceous Grayson Marl and Main Street Limestone Formation, undivided. Subsurface conditions consisted of fill materials, clay soils, and clayey sand soils over weathered to unweathered limestone and weathered to unweathered shale. Subsurface Conditions Fill materials were encountered at the surface of Boring No. 4. These fill materials consisted of dark brown to light brown clay soils that continued to a depth of 9 feet below existing grade. This fill was moderately plastic (CL) and contained varying amounts of calcareous particles and subangular gravel. Residual clay soils were present below the fill materials in Boring No. 4 and at the surface of Boring Nos. 1 through 3. These clays were dark brown to light brown in appearance, moderately plastic (CL), contained varying amounts of calcareous particles and limestone fragments. This clay continued to depths of 4 to 19 feet below existing grades. Clayey sand soils were encountered underlying the clays in Boring No. 1. These clayey sands were fine-grained, very dense (relative density), light brown in appearance, and continued to a depth of 13-1/2 feet below existing grade. Weathered shale was encountered underlying the clay soils in Boring Nos. 3 and 4. This weathered shale was soft (rock hardness classification), laminated in structure, light brown, light gray, and gray in appearance, and continued to depths of 18 to 20 feet below existing grades. It should be noted that Boring No. 4 terminated within the weathered shale at a depth of 20 feet. Unweathered shale was encountered underlying the clayey sand soils in Boring No. 1 and below the weathered shale in Boring No. 3. This unweathered shale was firm, dark gray in appearance, laminated in structure, and extended through the termination depths of the borings. Weathered limestone was present below the clay soils in Boring No. 2. This weathered limestone was tan in appearance, moderately hard, and continued to a depth of 12 feet below existing grade. Unweathered limestone was encountered underlying the weathered limestone. This unweathered limestone was hard, gray in appearance, and extended through the termination depth of the boring. Ground Water Ground water was encountered in Boring No. 1 during the field investigation at a depth of 10 feet below existing grade, and at a depth of 6 feet below existing grade at end of day observations. The presence and depth to ground water will vary depending upon seasonal rainfall amounts. When present, ground water should be expected to perch above the unweathered rock, migrating through the open cracks, fissures, and fractures of the overlying weathered rock and overburden soils. Report No. 19829G May 2, 2019 -3 - Excavations Per Federal regulations, any excavation over 20 feet in depth will require an engineered excavation and safety plan prepared by a licensed engineer. Soils encountered within the borings consisted of fill materials, CL clays, and clayey sands over weathered to unweathered limestone and shale. These soils should be classified as Type C soils per OSHA Excavation Standards CFR 29, Part 1926, Sub-Part P, Appendix A. Clay soils along the water lines may be laid back on a temporary slope of 1:Horizontal to 1:Vertical up to a maximum slope height of 20 feet. For retention system design, the on-site soils may be considered to exert an equivalent fluid pressure of 50 pcf considering active conditions against any shielding or temporary shoring. All spoils and construction materials should be kept a minimum of 4 feet from the edge of the trench. Water should not be allowed to pond along the edge of or within the bottom of the trench. Earthwork Recommendations On-site soils to be used all fill should be cleaned of all debris and rock fragments over 3-inches in nominal diameter. These materials should be placed in maximum eight-inch loose lifts and compacted to a minimum of 95% of the maximum density as determined by ASTM D-698. Moisture content should be at least +2 percentage points above optimum. Excavated limestone used as fill should be reduced to a maximum nominal diameter of 3 inches and placed in maximum 8-inch loose lifts. Limestone fragments should be compacted to a minimum of 95% (ASTM D-698) with moisture contents between –2 and +3 percentage points of optimum. Construction Testing and Observation It is recommended that all backfill materials within the trench be tested for moisture and density at a rate of one test per foot of fill for every 300 linear feet of excavation (NCTCOG Public Works Construction Standards, Fifth Edition – 2017, Item 504.5.3.2). Field density tests should be taken during placement of trench backfill. Excavating and evaluating fill materials within test pits should not be permitted. Provisions should be made to permit safe access to the utility trench during placement of fill to allow for testing of the backfill materials for adequate moisture and density. PLATE 1 LEGEND SOIL BORING HJA No.: DATE: 19829G APRIL 2019 TEXAS FIRM REGISTRATION NO. F-1238 BORING LOCATION PLAN235 MORGAN AVE. DALLAS, TX 75203 I 214.941.3808 I WWW.HJA-ENG.COM 3 4 US HIGHWAY 380 WATERLINE US HIGHWAY 380 AND I-35 DENTON, TEXAS 1 2 GEOTECHNICAL INVESTIGATION REPORT NO. 19829G US HIGHWAY 380 WATERLINE US HIGHWAY 380 AND I-35 DENTON, TEXAS Plate 2 SUMMARY OF INDEX PROPERTIES BORING NUMBER DEPTH (ft.) LIQUID LIMIT (%) PLASTIC INDEX DUW (pcf) FINER #200 (%) MOISTURE CONTENT (%) UNIFIED SOIL CLASSIFICATION 1 0.0 – 1.0 14.6 1 1.0 – 2.0 11.4 1 2.0 – 3.0 35 22 118.2 12.8 CL 1 3.0 – 4.0 16.0 1 4.0 – 5.0 18.5 1 5.0 – 6.0 21.8 1 8.5 – 10.0 21.7 2 0.0 – 1.0 22.9 2 1.0 – 2.0 18.3 2 2.0 – 3.0 16.3 2 3.0 – 4.0 35 22 15.8 CL 2 4.0 – 5.0 13.5 2 5.0 – 6.0 116.8 17.2 2 6.0 – 7.0 14.7 3 0.0 – 1.0 28.9 3 1.0 – 2.0 11.1 3 2.0 – 3.0 14.8 3 3.0 – 4.0 17.3 3 4.0 – 5.0 16.6 3 5.0 – 6.0 22.8 3 6.0 – 7.0 21.7 3 7.0 – 8.0 42 28 18.9 CL 3 8.0 – 9.0 21.4 3 9.0 – 10.0 102.9 24.5 3 14.0 – 15.0 22.1 4 0.0 – 1.0 14.9 4 1.0 – 2.0 13.1 4 2.0 – 3.0 17.7 GEOTECHNICAL INVESTIGATION REPORT NO. 19829G US HIGHWAY 380 WATERLINE US HIGHWAY 380 AND I-35 DENTON, TEXAS Plate 3 SUMMARY OF INDEX PROPERTIES BORING NUMBER DEPTH (ft.) LIQUID LIMIT (%) PLASTIC INDEX DUW (pcf) FINER #200 (%) MOISTURE CONTENT (%) UNIFIED SOIL CLASSIFICATION 4 3.0 – 4.0 109.6 20.5 4 4.0 – 5.0 22.4 4 5.0 – 6.0 22.1 4 6.0 – 7.0 48 32 23.4 CL 4 7.0 – 8.0 24.1 4 8.0 – 9.0 28.8 4 9.0 – 10.0 25.8 4 14.0 – 15.0 19.7 4 19.0 – 20.0 23.7 SUMMARY OF UNCONFINED COMPRESSION TESTS - SOIL BORING NUMBER DEPTH (ft.) PEAK STRESS (psi) FAILURE STRAIN (%) MATERIAL DESCRIPTION 1 2.0 – 3.0 74.5 6.3 CLAY, very stiff to hard, dark brown 2 5.0 – 6.0 15.6 7.5 CLAY, very stiff to hard, brown and light brown 3 9.0 – 10.0 21.9 6.2 SHALE, weathered 4 3.0 – 4.0 19.1 9.3 FILL: CLAY, very stiff to hard, brown and light brown Strata symbols LOW PLASTICITY CLAYS, SANDY CLAYS, OR GRAVELLY CLAYS (CL) CLAYEY SAND OR CLAYEY GRAVELLY SAND (SC) SHALE, unweathered HIGH PLASTICITY CLAYS (CH) LIMESTONE, weathered LIMESTONE, unweathered SHALE, weathered FILL Misc. Symbols Ground Water During Drilling (ft) Pocket Penetrometer (tsf) Standard Penetration (BPF) TxDOT CPT (inches per 100 blows) LEGEND, LITHOLOGY, SOIL CONSISTENCY & RELATIVE ROCK HARDNESS # OF BORINGS:4 PROJECT No.:19829G US Highway 380 Waterline US Highway 380 and I-35 Denton, Texas DRILL DATE:4/23/19 TEXAS FIRM REGISTRATION NO. F-1238 METHOD:Shelby Tube to 20' asdf FOR SANDS, GRAVELS, & SANDY SILTS FOR CLAYS AND SANDY CLAYS Modified from Peak, Hanson & Thornburn (1974) (COHESIVE SOILS) Modified from Peak, Hanson & Thornburn (1974) Consistency Standard Penetration Resistance (N) Consistency Unconfined Compression (tsf) Standard Penetration Resistance (N) Very Soft Less than 0.25 Less than 2 Very Loose Less than 4 Soft 0.25 to 0.5 2 to 4 Loose 4 to 10 Medium Stiff 0.5 to 1.0 4 to 8 Medium Dense 10 to 30 Stiff 1.0 to 2.0 8 to 15 Dense 30 to 50 Very Stiff 2.0 to 4.0 15 to 30 Very Dense Greater than 50 Hard Greater than 4.0 Greater than 30asdfasdf RELATIVE HARDNESS MODIFIERS (ROCK) (RELATED TO FRESH SAMPLE) Modified from SCS EWP, Tech Guide No. 4 Hardness Rule of Thumb Test Soft Permits denting by moderate finger pressure Resists denting by fingers but can be penetrated by pencil point to medium to shallow depth (No. 2 pencil)Firm Very shallow penetration of pencil point, can be scratched by knife and in some instances cut with knifeMod. Hard Hard No pencil penetration, can be scratched with knife, can be broken by light to moderate hammer blows Very Hard Cannot be scratched by knife, can be broken by repeated hammer blows asdf Soil Samplers Undisturbed thick wall Shelby tube Auger bag sample Split Spoon TxDOT CPT LEGEND, LITHOLOGY, SOIL CONSISTENCY & RELATIVE ROCK HARDNESS # OF BORINGS:4 PROJECT No.:19829G US Highway 380 Waterline US Highway 380 and I-35 Denton, Texas DRILL DATE:4/23/19 TEXAS FIRM REGISTRATION NO. F-1238 METHOD:Shelby Tube to 20' asdf FOR SANDS, GRAVELS, & SANDY SILTS FOR CLAYS AND SANDY CLAYS Modified from Peak, Hanson & Thornburn (1974) (COHESIVE SOILS) Modified from Peak, Hanson & Thornburn (1974) Consistency Standard Penetration Resistance (N) Consistency Unconfined Compression (tsf) Standard Penetration Resistance (N) Very Soft Less than 0.25 Less than 2 Very Loose Less than 4 Soft 0.25 to 0.5 2 to 4 Loose 4 to 10 Medium Stiff 0.5 to 1.0 4 to 8 Medium Dense 10 to 30 Stiff 1.0 to 2.0 8 to 15 Dense 30 to 50 Very Stiff 2.0 to 4.0 15 to 30 Very Dense Greater than 50 Hard Greater than 4.0 Greater than 30asdfasdf RELATIVE HARDNESS MODIFIERS (ROCK) (RELATED TO FRESH SAMPLE) Modified from SCS EWP, Tech Guide No. 4 Hardness Rule of Thumb Test Soft Permits denting by moderate finger pressure Resists denting by fingers but can be penetrated by pencil point to medium to shallow depth (No. 2 pencil)Firm Very shallow penetration of pencil point, can be scratched by knife and in some instances cut with knifeMod. Hard Hard No pencil penetration, can be scratched with knife, can be broken by light to moderate hammer blows Very Hard Cannot be scratched by knife, can be broken by repeated hammer blows asdf 0 3 6 9 12 15 18 21 CLAY, with limestone fragments, very stiff to hard, dark brown CLAYEY SAND, fine-grained, very dense, light brown SHALE, laminated, firm, dark gray TOTAL DEPTH: 15.0' 50=3.75" 60 LOG OF BORING PROJECT No.:19829G US Highway 380 Waterline US Highway 380 and I-35 Denton, Texas BORING No.:1 STATION: DRILL DATE:4/23/19 SHEET:1 of METHOD:Shelby Tube w/Split Spoon to 15'LOCATION:See Plate 1 GROUND ELEVATION: Ground Water During Drilling (ft.):10' dfs Ground Water After Drilling (ft.):6'DEPTH(feet)SYMBOLSAMPLESMATERIAL DESCRIPTION ELEVATION(feet)RECOVERED (ft.)CORE RQD (%)1 2 3 4 +++POCKET PENETROMETER (tsf) 10 20 30 40 50 60STANDARD PENETRATION (BPF) 1 2 3 4 5 6 TxDOT CPT (inches per 100 blows) 1 0 3 6 9 12 15 18 21 CLAY, calcareous, very stiff, dark brown CLAY, with limestone fragments, very stiff to hard, brown and light brown LIMESTONE, weathered, moderately hard, tan LIMESTONE, hard, gray TOTAL DEPTH: 15.0' 1.5" 0.75" LOG OF BORING PROJECT No.:19829G US Highway 380 Waterline US Highway 380 and I-35 Denton, Texas BORING No.:2 STATION: DRILL DATE:4/23/19 SHEET:1 of METHOD:Shelby Tube to 15'LOCATION:See Plate 1 GROUND ELEVATION: Ground Water During Drilling (ft.):DRY dfs Ground Water After Drilling (ft.):DRYDEPTH(feet)SYMBOLSAMPLESMATERIAL DESCRIPTION ELEVATION(feet)RECOVERED (ft.)CORE RQD (%)1 2 3 4 +++POCKET PENETROMETER (tsf) 10 20 30 40 50 60STANDARD PENETRATION (BPF) 1 2 3 4 5 6 TxDOT CPT (inches per 100 blows) 1 0 3 6 9 12 15 18 21 CLAY, very stiff, dark brown CLAY, with limestone fragments, very stiff, brown and light brown SHALE, weathered, laminated, soft, light brown and gray SHALE, laminated, firm, dark gray TOTAL DEPTH: 20.0' 6.75" LOG OF BORING PROJECT No.:19829G US Highway 380 Waterline US Highway 380 and I-35 Denton, Texas BORING No.:3 STATION: DRILL DATE:4/23/19 SHEET:1 of METHOD:Shelby Tube to 20'LOCATION:See Plate 1 GROUND ELEVATION: Ground Water During Drilling (ft.):DRY dfs Ground Water After Drilling (ft.):DRYDEPTH(feet)SYMBOLSAMPLESMATERIAL DESCRIPTION ELEVATION(feet)RECOVERED (ft.)CORE RQD (%)1 2 3 4 +++POCKET PENETROMETER (tsf) 10 20 30 40 50 60STANDARD PENETRATION (BPF) 1 2 3 4 5 6 TxDOT CPT (inches per 100 blows) 1 0 3 6 9 12 15 18 21 FILL: CLAY, with subangular gravel, very stiff to hard, brown and light brown FILL: CLAY, calcareous, stiff to very stiff, dark brown and brown CLAY, calcareous, very stiff, brown CLAY, with calcareous nodules, very stiff, light brown SHALE, weathered, laminated, soft, light brown and light gray TOTAL DEPTH: 20.0' LOG OF BORING PROJECT No.:19829G US Highway 380 Waterline US Highway 380 and I-35 Denton, Texas BORING No.:4 STATION: DRILL DATE:4/23/19 SHEET:1 of METHOD:Shelby Tube to 20'LOCATION:See Plate 1 GROUND ELEVATION: Ground Water During Drilling (ft.):DRY dfs Ground Water After Drilling (ft.):DRYDEPTH(feet)SYMBOLSAMPLESMATERIAL DESCRIPTION ELEVATION(feet)RECOVERED (ft.)CORE RQD (%)1 2 3 4 +++POCKET PENETROMETER (tsf) 10 20 30 40 50 60STANDARD PENETRATION (BPF) 1 2 3 4 5 6 TxDOT CPT (inches per 100 blows) 1