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HomeMy WebLinkAboutSTONEBRIDGE GARDEN APARTMENTS PRELIM PUD - 82 93 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTEmpire Laboratories, Inc. MATERIALS AND FOUNDATION ENGINEERS 214 No. Howes Fort Collins, Colorado 80522 P.O. Box 429 (303) 48"359 :ctober 17, 1980 Z'iF::, Architects/Planners C13 nest ;Mountain avenue Fort Collins, Colorado 30521 Attention: ;'4r. Ed Zdenek Gentlemen: Branch Offices 1242 Bramw000 Place Longmont, Colorado 80501 P.O. Box 1135 (303) 776-3921 3151 Nation Way Cheyenne, Wyoming 82001 P.O. Box 10076 (307) 632-9224 We are pleased to submit our Report of a Ceotechnical Investigation prepared for the proposed Golden Meadows Neighborhood Center, Larimer County, Colorado. The subsurface conditions revealed by this investigation are suitable for the intended construction, provided construction is in accordance with the recosendations contained in this report. ne attached report presents the subsurface conditions at the site and our reconr..endations for development of the site. de appreciate this opportunity of consulting with you on this project. If you have any questions or if we can be of further assistance, please contact us. Very truly yours, FM; p ' E LABORATORRIIES, IINNC. je�James E. Veith, P.E. Geotechnical Engineer Rev i ewed�by�: Chester C. Smith, P.E. President cic cc: Collindale South II - Bill Tiley MEMBER OF CONSULTING ENGINEERS COUNCIL \0% :< DES E. Vic' -, O e 'fnp LOG OF BORINGS 4980 4975 4970 4965 4960. • iAM sue •� WIN -�-Arm EVA Arm ®�iv- E A- 6 EMPIRE LABORATORIES, INC. BORING NO. DEPTH FT. % MOISTURE 13 0.5-1.5 16.3 3.0-4.0 16.6 4.0-5.0 7.0-8.0 14.5 8.0-9.0 13.5-14.5 18.4 W 14 0.5-1.5 10.7 3.0-4.0 10.3 .4.0-5.0 7.0-8.0 7.3 .. 8.0-9.0 13:5-14.5 21.0 18.5-19.5 19.8 23.5-24.5 10.5 28.5-29.5 23.2 33.5-33.9 15.1 SUMMARY OF TEST RESULTS DRY DENSITY UNCONFINED COMPRESSIVE P.C.F. STRENGTH-P.S.F. 112.3 1 3,970 186.7 29600 102.2 29310 WATER SOLUBLE SULFATES-% PENETRATION (LOWS/INCHES 15/12 5/12 4/12 8/12 15/12 6/12 7/12 4/12 11/12 23/ 12 10/12 50/ 5 EMPIRE LABORATORIES, INC. pneumatic -tired rollers, three -wheel power rollers, vibratory compactors, or other approved equipment well -suited to the soil being compacted. If a sheepfoot roller is used, it shall be provided with cleaner bars attached in a manner which will prevent the accumulation of material between the tamper feet. The rollers should be designed so that effective weight can be increased. MOISTURE -DENSITY DETERMINATION Samples of representative fill materials to be placed shall be furnished •by the contractor to the soils engineer for determination of maximum density and optimum moisture or percent of Relative Density for these materials. Tests for this determination will be made using methods conforming to requirements of ASTM D 698, ASTM D 1557, or ASTM D 2049. Copies of the results of these tests will be furnished to the owner, the project engineer, and the contractor. These test results shall be the basis of control for all compaction effort. DENSITY TESTS The density and moisture content of each layer of compacted fill will be determined by the soils engineer in accordance with ASTM D 1556, ASTM D 2167, or ASTM D 2922. Any material found not to comply with the minimum specified density shall be recompacted until the required density is obtained. Sufficient density tests shall be made and submitted to support the soils engineer's recommendations. The results of density. tests will also be furnished to the owner, the project engineer, and the contractor by the soils engineer,. V C-4 PLACING FILL No sod, brush, frozen or thawing material, or other unsuitable material shall be placed in the fill, and no fill shall be placed during unfavorable weather conditions. All clods shall be broken into small pieces, and distribution of material in the fill shall be such as to preclude the formation of lenses of.material differing from the surrounding material. The materials shall be delivered to and spread on the fill surface in a manner which will result in a uniformly compacted fill. Each layer shall be thoroughly blade mixed during spreading to insure uniformity of material and moisture in each layer. Prior to compacting, each layer shall have a maximum thickness of eight inches, and its upper surface shall be approximately horizontal. Each successive 6" to 8" lift of fill being placed on slopes or hillsides should be benched into the existing slopes, providing good bond between the fill and existing ground. MOISTURE CONTROL While being compacted, the fill material in each layer shall as nearly as practical contain the amount of moisture required for optimum compaction or as specified, and the moisture shall be uniform throughout the fill. The contractor may be required to add necessary moisture to the fill material and to uniformly mix the water with the fill material if, in the opinion of the soils engineer, it is not possible to obtain uniform moisture content by adding water on the fill surface. If, in the opinion of the soils engineer, the material proposed for use in the compacted fill is too wet to permit adequate compaction, it shall be dried in an acceptable manner prior to placement and compaction. COMPACTION When an acceptable, uniform moisture content is obtained, each layer shall be compacted by a method acceptable to the soils engineer and as specified in the foregoing report as determined by applicable* standards. Compaction shall be performed by rolling with approved tamping rollers, C-3 APPENDIX C. Suggested Specifications for Placement of Compacted Earth Fill and/or Backfills. i GENERAL A soils engineer shall be on -site to provide continuous observation during filling and grading operations and shall be the owner's repre- sentative to inspect placement of all compacted fill and/or backfill on the project. The soils engineer shall approve all earth materials prior to their use, the methods of placing, and the degree of compaction obtained. MATERIALS Soils used for all compacted fill and backfill shall be approved by the soils engineer prior to their use. The upper two (2) feet of compacted earth backfill placed adjacent to exterior foundation walls shall be an impervious, nonexpansive material. No material, including rock, having a maximum dimension greater than six inches shall be placed in any fill. Any fill containing rock should be carefully mixed. to avoid nesting and creation of voids. In no case shall frozen material be used as a fill and/or backfill material. - PREPARATION OF SUBGRADE All topsoil, vegetation (including trees and brush); timber, debris, rubbish, and other unsuitable material shall be removed to a depth satisfactory to the soils engineer and disposed of by suitable means before beginning preparation of the subgrade. The subgrade.surface of the'area to be filled shall be scarified a minimum depth of six inches, moistened as necessary, and compacted in a manner specified below for the subsequent layers of fill. Fill shall not be placed on frozen or muddy ground. r.-2 6 SUMMARY OF TEST RESULTS Atterberg Summary Boring No. 11 12 24 25 30 31 32 33 34 Depth (Ft.) 1.0-2.0 1.0-2.0 1.0-2.0 1.0-2.0 1.0-2.0 1.0-2.0 1.0-2.0 1.0-2.0 1.0-2.0 Liquid Limit 35.8 28.7 28.9 31.7 37.2 35.5 37.2 35.9 38.3 Plastic Limit 19.6 15.1 17.5 16..7 18.0 19.0 19.5 20.9 19.5 Plasticity Index 16.2 13.5 ll.4 15.0 19.2 16.5 17.7 14.9 18.8 % Passing 200 76.9 63.9 42.8 69.8 78.6 58.9 56.5 41.1 75.4 Group Index 11.3 5.9 1.5 8.3 14.0 7.1 7.2 2.4 13.1 Classification Unified CL CL SC CL CL CL CL SC CL AASHTO A-6(11) A-6(6) A-6(2) A-6(8) A-6(14) A-6(7) A-6(7) A-6(2) A-6(13) SUMMARY OF TEST RESULTS Swelling Pressures Boring Depth % Moisture Dry Density Swelling No. (Ft.) Before Test P.C.F. Pressure PSF 3 3.0-4.0 14.5 104.5 620 4 3.0-4.0 11.8 95.0 240 8 3.0-4.0 13.3 91.5 20 21 3.0-4.0 12.7. 115.7 1345 22 3.0-4.0 11.2 89.9 115 25 1.0-2.0 11.2 105.4 550 26 3.0-4.0 12.7 108.6 515 28 3.0-4.0 11.0 107.4 760 SUMMARY OF TEST RESULTS DEPTH FT. % MOISTURE DRY DENSITY P.C.F. UNCONFINED COMPRESSIVE STRENGTH-P.S.F. WATER SOLUBLE SULFATES-% PENETRATION BLOWS/INCHES BORING NO. 32 1.0-2.0 10.5 107.8 13,530 2.0-3.0 14/12 6.0-7.0 6.5 15/12 33 1.0-2.0 9.6. 2.0-3.0 11/12 6.0-7.0 14.0 9/12 34 1.0-2.0 12.2 103.6 109060 2.0-3.0 I 12/12 6.0-7.0 15.4 8/12 " EMPIRE LABORATORIES, INC. NO. BORINGt3. DEPTH FT. % MOISTURE 28.5-1.5 11.6 0-4.0 11.0 4.0-5.0 7.0-8.0 12.5 8.0-9.0 13.5-14.5 17.2 18.5-19.0 12.5 O0 29 1.0-2.0 18.3 o, 2.0-3.0 6.0-7.0 12.0 30 1.0-2.0 12.8 2.0-3.0 15.6 6.0-7.0 16.2 31 1.0-2.0 11.1 2.0-3.0 6.0-7.0 13.6 SUMMARY OF TEST RESULTS DRY DENSITY UNCONFINED COMPRESSIVE P.C.F. STRENGTH-P.S.F. 109.7 139460 109.6 52410 112.1 1 129250 110.3 1 139810 WATER SULFA PENETRATION BLOWS/ INCHES 14/12 19/12 6/12 9/12 50/6 5/12 8/ 12 14/12 5/12 13/12 3/12 EMPIRE LABORATORIES, INC. BORING NO. DEPTH FT. % MOISTURE 24 1.0-2.0 9.0 2.0- 3.0 6.0-7.0 18.8 7.0- 8.0 13.5-14.5 4.3.. 25 1.0-2.0 11.2 2.0-3.0 W 6.0-7.0, 8.9 ' 26 0.5-1.5 10.6 3.0-4.0 12.7 4.0- 5.0 7.0-8.0 21.5 8.0-9.0 13.5-14.5 22.8 27 0.5-1.5 11.4 3.0-4.0 10.8 4.0-5.0 7.0-8.0. 15.2 8.0-9.0 13.5-14.5 21.9 SUMMARY OF TEST RESULTS DRY DENSITY UNCONFINED COMPRESSIVE P.C.F. STRENGTH-P.S.F. 107.5 41450 109.0 1 . 119930 100.8 89.9 1,670 98.4 52610 106.6 39330 WATER SOLUBLE SULFATES-% .0150 NS/ INCHES 11/12 11/12 9/12 12/12 21/12 10/12 6/ 12 2/12 4/ 12 9/12 9/12 4/12 22/12 EMPIRE LABORATORIES, INC. BORING NO. DEPTH FT. 1/0 MOISTURE 21 0.5-1.5 10.9 3.0-4.0 12.7 4.0-5.0 7.0- 890 21.9 8.0-9.0 13.5-14.5 23.8 W 22 0.5-1.5 14.6 3.0-4.0 11.2 4.0- 5.0 7.0-8.0 19.1 8.0-9.0 17.1 13.5-13.9 13.4 23 0.5-1.5 10.3 3.0-4.0 14.9 4.0-5.0 ' 7.0-8.0 7.0 8.0-9.0 13.5-13.9 12.5 SUMMARY OF TEST RESULTS DRY DENSITY UNCONFINED COMPRESSIVE P.C.F. STRENGTH-P.S.F. 115.8 209800 98. 7- 29880 105.2 I 77,870 117.0 WATER SOLUBLE SULFATES-% PENETRATION BLOWS/ INCHES 20/12 19/12 8/ 12 7/ 12 13/12 15/12 31/12 50/ 5 13/12 20/12 14/12 50/ 5 EMPIRE LABORATORIES, INC. BORING NO. DEPTH FT. % MOISTURE 18 0.5-1.5 11.1 3.0-4.0 12.4 4.0-5.0 7.0-8.0 11.5 8.0-9.0 13.5-14.5 24.2 19 0.5-1.5 13.3 3.0-400 12.4 4.0-5.0 7.0-8.0 19.7 8.0-9.0 13.5-14.5 20.6 20 0.5-1.5 11.7 3.024.0 13.9 4.0-5.0 7.0-8.0 26.0 8.0-9.0 13.5-14.5 26.2 18.5-19.5 14.4 23.5-24.4 19.5 SUMMARY OF TEST RESULTS DRY DENSITY UNCONFINED COMPRESSIVE P.C.F. STRENGTH-P.S.F. 100.5 69310 113.4 3,370 101.4 3,090 104.7 29910 107.8 15,370 98.0 930 WATER SOLUBLE SULFATES-% 0.0075 PENETRATION BLOWS/ INCHES 9/12 8/12 8/12 4/12 12/12 4/12 6/12 12/12 14/12 11/12 4/12 12/12 13/12 50/11 1' I EMPIRE LABORATORIES, INC. BORING NO. DEPTH FT. MOISTURE _ 15 0.5-1.5 13.0 3.0-4.0 9.8 4.0-5.0 7.0-8.0 16.7 8.0-9:0 13.5-14.5 22.1 16 0.5-1.5 10.2 3.0-4.0 9.8 . 4.0-5.0 7.0-8.0 11.9 8.0-9.0 13.5-14.5 23.7 17 0.5-1.5 10.0 3.0-4.0 4.0-5.0 12.3 7.0-8.0 13.8 8.0-9.0 13.5-14.5 20.5 SUMMARY OF TEST RESULTS DRY DENSITY UNCONFINED COMPRESSIVE P.C.F. STRENGTH-P.S.F. 92.6 105.6 2, 390 86.8 3,660 97.8 110.6 1 39230 WATER SULFA PENETRATION BLOWS/ INCHES 17/12 7/12 5/12 5/12 13/12 11/12 10/12 10/12 11/12 11/12 5/12 7/12 EMPIRE LABORATORIES, INC. d BORING NO. DEPTH FT. 0.5-1.5 % MOISTURE 14.6 10 3.Om- 4.0 9.8 4.0-5.0 7.0-8.0 14.7 8.0-9.0 13.5-14.5. 22.2 11 1.0-2.0 13.6 W 'r 2.0-3.0 0 6.0-7.0 14.8 7.0-8.0 .13.5-14.5 19.3 12 1.0-2.0 13.5 2.0-3.0 6.0-7.0 18.9 - 7.0- 8.0 13.5-14.5 24.3 SUMMARY OF TEST RESULTS DRY DENSITY UNCONFINED COMPRESSIVE P.C.F. STRENGTH-P.S.F. 96.7 1 29410 97.8 39850 110.7 109470 105.7 119240 103.8 4,230 WATER SOLUBLE SULFATES-% PENETRATION BLOWS/ INCHES 12/12 10/12 9/12 4/12 8/12 26/12 11/12 9/12 8/ 12 5/12 L EMPIRE LABORATORIES, INC. BORING NO. DEPTH FT. % MOISTURE 7 0.5-1.5 9.6 3.0-4.0 7.0 4.0-5.0 7.0-8.0 6.7 8.0-9.'0 13.5-14.5 18.4 8 0.5-1.5 12.6 w 3.0-4.0 13.3 4.0-5.0 7.0-8.0 12.3 8.0-9.0 13.5-14.5 22.6 18.5-19.5 20.3 23.5-24.5 23.2 28.5-29.2 17.5 9 0.5-1.5 10.7 3.0-4.0 10.9 4.0-5.0 7.0-8.0 8.2 8.0-9.0 13.5-14.5 17.1 SUMMARY OF TEST RESULTS SITY DRYDENSITYT P.C.F. UNCONFINEDCOMPRESSIVE STRENGTH-P.S.F. E SULFATES-% PENETRATION BLOWS/INCHES 19/12 17/12 16/12 7/12 15/12 91.8 29520 19/12 111.0 139000 14/12 7/12 10/12 19/12 .0200 50/8 10/12 86.1 19030 6/12 8/12 10/12 EMPIRE LABORATORIES, INC. BORING NO. 4 y 6 0.5-1 .5 3.0-4.0 4.0-5.0 7.0-8.0. 8.0-9.0 13.5-14.5 0.5-1.5 3.0-4.0. 4.0-5.0 7.0- 8.0 13.5-14.5 0.5-1.5 3.0-4.0 4.0- 5.0 7.0- 8.0 8.0-9.0 13.5-14.5 SUMMARY OF TEST RESULTS % . DRY DENSITY UNCONFINED COMPRESSIVE MOISTURE P.C.F. STRENGTH-P.S.F. 11.7 11.8 10.5, 21.5 10.4 9.1 8.5 23.6 13.8 8.5 6.5 20.4, a 103.0 139200 111.0 14,550 107.6 1 12,980 90.8 1,190 112.9 69320 WATER SOLUBLE SULFATES-% PENETRATION ILOWS/ INCHES 11/12 13/12 20/12 12/12 16/12 13/12 11/12 8/ 12 12/12 12/12 4/12 6/12 EMPIRE LABORATORIES, INC. BORING NO. DEPTH FT. 0.5-1.5 % MOISTURE 14.0 1 3.0-4.0 7.9 4.0-5.0 7.0-8.0 13.2 8.0-9.0 13.5-14.5 24.6 18.5-19.5 16.8 23.5-24.5 19.3 28.5-29.0 17.4 2 0.5-1.5 3.0-4.0 16.8 4.0- 5.0 7.0-8.0 18.1 8.0-9.0 13.5-14.5. 14.0 3 0.5-1.5 16.0 33.0-4.0 14.5 4.0-5.0 7.0-8.0 15.3 8.0-9.0 13.5-14.5 10.9 SUMMARY OF TEST RESULTS DRYDENSITYUNCONFINED P. SSIVE STRENGTH-P.S.F. E SULFATES-% PENETRATION BLOWS/INCHES 10/12 107.7 39830 12/12 .0200 2/12 6/12 10/12 28/12 50/ 6 11/12 88.0 29070 6/12 104.7 21930 3/ 12 22/12 10/12 111.3 189740 15/12 108.0 3,280 4/ 12 19/12 EMPIRE LABORATORIES, INC. .75. o .70 0 a .65 .6 J J z 5 0 a c z 0 u 10 CONSOLIDATION --SWELL TEST BORING No,16 DEPTH lie 1110111111111111111111110, sill Is �■■maims■■��m 0.1 0.5 1.0 S 10 APPLIED PRESSURE-TONS/SQ. FT. 0.1 0.5 1.0 APPLIED PRESSURE-TONS/SQ. FT. B- 6 s 10 70 .65 .5F CONSOLIDATION --SWELL TEST BORING NO. 15 DEPTH 3.0 DRY DENSITY 97.7#/Ft3 i °o MOISTURE Q _ R a 1 I I I i j II 1 i i 0.1 0.5 1.0 5 lc APPLIED PRESSURE—TONS/SQ. FT. 0.1 0.5 1.0 APPLIED PRESSURE—TONS/SQ. FT. B-5 FMPIRF I ARC',ZATCIRIFS INC.. 5 10 CONSOLIDATION --SWELL TEST .85 BORING NO. 13 DEPTH 3. 0 j DRY DENSITY 8 _-_6_ Ft3 % MOISTURE 16. 6 0 f .80 I N i 0 .75 i a I 0 I 0 I f i .70 � i i i . I .65 j 0.1 0.5 1.0 S l0i APPLIED PRESSURE—TONS/SQ. FT. 0 0.1 0.5 1.0 APPLIED PRESSURE—TONS/SQ. FT. B- 4 cuDiDc IAOnDATnoicc u.il- 5 10 .40 .35 0.1 CONSOLIDATION --SWELL TEST 0.5 1.0 APPLIED PRESSURE—TONS/SQ. FT. s 3 1C 0.1 0.5 1.0 5 10 APPLIED PRESSURE—TONS/SQ. FT. B-3 ru nrnr . . n.�:� • �.•. n.rn ui- .75 .70 0 a 0 o .65 .60 .55 0 CONSOLIDATION --SWELL TEST APPLIED PRESSURE-TONS/SQ. FT. i a 0.5 1.0 s to APPLIED PRESSURE-TONS/SQ. FT. B- 2 APPENIDIX B. LOG OF BORINGS 4975 LU No. 3Z No. 33 tia z4 ti mill ow -sue Glm A-12 EMPIRE LABORATORIES, INC. 4975 4970 4965 LOG OF BORINGS - :� - - A-11 EMPIRE LABORATORIES, INC. LOG OF BORINGS /\� No.25 �110.26 IVa.27 No.ZB 4980 4975 4970 4965 4960 4955 v� r-WAR ' iAW M EW �wiaw i MAE ��z-- • m WA WAAF r® &V m� 50/6 m A- l 0 EMPIRE LABORATORIES, INC. ••1 4975 4970 4965 4960 LOG OF BORINGS d( kl/ 2-1 Vo.27 fJo.23 Nim,24 11 12 20/12 13 r. 13/12 -- �r 11112 19/12 152 /1 20/12 c: " • . i 7 8/12 31 / 12 14 / 1 2 — — 9/12 7 1 2 50/ 5 50/ 5 A-9 EMPIRE LABORATORIES, INC. 4980 4975 4970 4965 4960 4955 4950 LOG OF BORINGS MCI C��:�ii© FAFA -� -�� M-� RIM s� i� A- 8 EMPIRE LABORATORIES, INC. LOG OF BORINGS .m 4975 4970 m-l" 4960 4955 4950 t0 In.1.13 _vim era •rr� OVA� FlAr-_�®a FIA o� 23/12 i� m m A- 7 EMPIRE LABORATORIES, INC. LOG OF BORINGS ,m 4975 4970 4965 4960 4955 4950 vm -WAI E� �� I OR N® see A- 5 EMPIRE LABORATORIES, INC. LOG OF BORINGS mel 4975 4970 4965 4960 4955 4950 �►AI m w/ r; a� rrtmm�M m A W • w Qo. ms� mo Q7 m NOTE: Elevations interpolated from a topographic plan prpoarPd by ZVFK. A— 4 EMPIRE LABORATORIES, INC. KEY TO BORING LOGS TOPSOIL �•��� GRAVEL ®.: FILL ,'" SAND & GRAVEL i� SILT i SILTY SAND & GRAVEL CLAYEY SILT o ea COBBLES DSANDY SILT SAND, GRAVEL & COBBLES ® CLAY ® WEATHEREDBEDROCK SILTY CLAY e SILTSTONE BEDROCK ZA SANDY CLAY ® CLAYSTONE BEDROCK aSAND SANDSTONE BEDROCK '•�� i ... SILTY SAND Ltd. 'LIMESTONE CLAYEY SAND GRANITE SANDY SILTY CLAY F SHELBY TLIBE SAMPLE - STANDARD PENETRATION DRIVE SAMPLER 5 WATER TABLE 24 HOURS AFTER DRILLING T HOLE CAVED 5/12 Indicates that 5 blows of a 140 pound hammer falling 30 inches was required to penetrate 12 inches. A-3 EMPIRE LABORATORIES, INC. TEST BORING LOCATION PLAN Na32 9 'w'HE-41rom t-,>R. Ua B No.26 1 L-ML1RFt4Y /SVE.. EMPIRE LABORATORIES, INC. MONTE— L/�RLO tsR. .W No Text (8) It is reconrnended that all cc-paction requirements specified herein be verified in the field with density tests performed under the direction of the geotechnical engineer. (7) It is recorxended that a registered professicnal engineer design the foundations usin+J the reccri:rendations presented in this report. CENE;AL CP"'AIM NTS This report has been prepared to aid in the evaluation of the property and to assist the architect and/or engineer in the design of this project. In the event that any changes in the design of the structures or their locations are planned, the conclusions and reco;=en- dations contained in this report will not be considered valid unless said changes are raviev:ed and conclusions of this report modified or approved in writing by Empire Laboratories, Inc., the soils engineer of record. Every effort was Trade to provide comprehensive site coverage through careful locations of the test borings, while keeping the site investigation economically feasible. Variations in soil and groundwater conditions between test borings may be encountered during construction. In order to permit correlation between the reported subsurface conditions and the actual. conditions encountered during construction and to aid in carrying out the plans and specifications as originally contemplated, it is recommended that Empire Laboratories, Inca be retained to perform continuous construction revie%i during the excavation and foundation phases of the work. Empire Laboratories, Inc. assumes no responsibility for corcpliance with the recorr.,endations included in this report unless they have been retained to perform adequate on -site construction review during -the course of construction. i i -U. The base course should be placed on the subgrade at or near opti tum moisture and compacted to at least ninety-five percent (95t) of Standard Proctor Density AST1 0 59°r73. (See Appendix C.) It is important that the base course be shaped to grade so that proper drainage of the pavement area is obtained. The asphaltic concrete should meet City of Fort Collins specifi- cations or equivalent and be placed in accordance with those speci- fications. GENERAL RECCW ENOATIONS (1). Laboratory tests indicate that water soluble sulfates in the soil are negligible, and a Tyne I cenent may be used in all concrete exposed to subsoils. All slabs on crade subjected to de-icing chemicals should be composed of a more durable con- crete using a Type Il cement with low water-ce%ent ratios and higher air contents. (2) Finished grade should be sloped away from the structures on all sides to give positive drainage. Five percent (5%) for the first five (5) feet away from the structures is the sug- gested slope. (3) 3ackfill around the outside perimeter of the structures should be mechanically compacted at optimum. toisture to at least ninety-five percent (95%) of Standard Proctor Density ASTM D 698-73. (See Appendix C.) Puddling should not be. permitted as a method of compaction. (4) Cutters and downspouts should be designed to carry roof runoff water well beyond the backfill area. (5) Underground sprinkling systems should not be installed within ten (10) feet of the structures, and this recoesr-endation should be taken into account in the landscape planning. Select Subbase Select Base Course Asphaltic Concrete Total Pavenent Thickness Collector Arterial 4" 1" 6u 6" 2" 2" 12" 15" pie understand that Monte Carlo and Wheaton Drives are both collector streets. Harmony Pzad to the south of the property is an arterial street. Within the proposed iWighborhood Center, the following pavement thicknesses are recom ended using the group index design procedure: Automobile Parking Service Drives Select Subbase --- 4" Select Base Course 1" 6" Asphaltic Concrete 2" 2" Total Pavement Thickness 9" 12" Hveem stabilcreter tests are presently being performed on representative samples of the subgrade materials. When these tests are completed, pavement thicknesses using the new City of Fort Collins design procedure will be submitted. At that time, we will also include concrete pavement alternatives. The base course overlying the subgrade should consist of a hard, durable, crushed rock or stone and filler and should .have a minimum "R• value of 80. The composite base course eraterial should be free .from vegetable matter and lumps or balls of clay and should meet the Colorado Department of Highways Specification Class 6 Aggregate Base Course >,ahich follows: sieve Size % Passing 3/4" 100 g4 30-65 08 25-55 1200 3-12 Liquid Limit - 30 Maximum Plasticity Index - 6 Maximum vation should be accomplished as discussed in the "Site Grading" section of this report. As previously discussed, the near -surface soils encoun- tered at the site are plastic and may be susceptible to swelling if they are allowed to dry below their in situ moisture contents and then are rewetted. To prevent drying of the clay soils, foundation and building excavations should not be allowed to remain open for extended periods of time. Slabs on grade supporting heavy f1cor loads should be underlain by at least six (6) inches of crushed gravel base course, placed at optimum moisture content and compacted to a minicium of ninety-five percent (95%) of Standard Proctor Censity ASTM 0 599-73. (See Appendix C.) Office and other areas transmitting li,ht floor loads should be underlain by a minimum of four (4) inches of cleangravel or crushed rock free of fines. The gravel base course and/or gravel will help to distribute floor loads and will act as a capillary break. All slabs on grade should be designed for the inposed loading, and it is suggested that they be designed and constructed structurally independent of all bearing members. To mininize and control shrinkage cracks which will develop in slabs on grade, we suggest that control joints be placed every twenty (20) to twenty-five (25) feet and that the total area contained within these joints be no greater than six hundred thenty-five (625) square feet. pavements preparation to pavement subgrade elevation should be accomplished as previously discussed in the "Site Grading" section of this report. AASHTd classification of the on -site near -surface materials forming pavement subgrade is A-6 with group indices 2 to 14. Using the group index design procedure and a group index of 13, the following pavement thicknesses are recorsaended: M thousand (309000) pounds per square foot. 4n estimated skin friction of three thousand (3000) pounds per square foot will be developed for that portion of the pier embedded into the fir-, bedrock stratum. To counter- act swelling pressures which will develop if the subsoils become wetted, all piers should be designed for a minirun dead load of ten thousand (10,000) pounds per square foot. Where this mini.ru^ dead load require- ment cannot be satisfied. skin friction from additional erbedrnent into the firm bedrock should be used to resist uplift. All piers should be reinforced their full length to resist tensile stresses created by swelling pressures acting on the pier. It is essential that all grade beams have a minimum four (4) inch void bet: -teen the bottom of the beam and the soil below. The anticipated settlement of piers under the above maximum loading should be negligible. Temporary casing of all pier holes Tay he required to prevent sloughing of the overburden materials and to permit dewatering prior to concreting. To facilitate, cleaning, dewatering, and inspection of piers, minimum twenty-four (24) inch diameter piers are recomended. It is recorrended that qualified geotechnical personnel be present during drilling operations to identify and verify penetration into the firm bedrock, make certain that all piers are of proper diameter and plumbness and that they are thoroughly cleaned and dewatered, and ensure that reinforcing steel and concrete are properly placed. Basements and Slabs on Grade The subsurface conditions encountered at the site Will permit exca- vations of basements if desired. We do recerr:end that the basem.eht finished floor be placed at least three (3) feet above groundwater levels encountered in this investigation and a minlmn of three (3) feet above the bedrock surface. Cue to the shallow bedrock encountered in Borings 22 and 23s basement construction may not be feasible in the extreme southeast corner of the property. The subsurface conditions at the site will also permit conventional slab -on -grade construction. Preparation to slab -on -grade subgrade ele- i tests should be taken daily to determine the degree of compaction being i i attained and corpliance wits protect specifications. j Foundations Used upon the subsurface conditions encountered at the site and the loads transmitted by the proposed construction, we recommend that all structures be supported by conventional continuous or isolated spread footings bearing in undisturbed natural soil or fill placed as recom,,ended above. As on -site materials will be used for fill. struc- tural fill placed and cempacte-i as reconrended above will have com- parable shear strength and bearing qualities to those of the in situ materials. Exterior footin;s should !year a mininun of thirty (N) inches below exterior finished grades for frost protection. The nature of the bearing soil should be verified by qualified geotechnical per - sonnet prior to placement of foundation concrete. Footings bearing at the above-recorvaended depths may be designed for a maximum allowable soil pressure of one thousand five hundred (1500) pounds per square foot under dead plus maximun live loads. To resist swelling pressures which will develop if the subsoils become wetted, footings should be designed for a minimum dead toad pressure of five' hundred (500) pounds per square foot. The anticipated settlement under the above-reco+rc:ended maximum pressures should not exceed three -fourths (3/4) inch. The overburden materials encountered at the site are plastic and may be susceptible to swelling if they are allowed to dry below their in situ moisture levels and then are rewetted. Therefore, to prevent drying of the clay soils below their in -place moisture levels, foundation and building excavations should not be allowed to remain open for ex- tended periods of time. As an alternatives the proposed structures can be supported on straight -shaft drilled piers end bearing in the bedrock formation. Piers drilled a minimum of three (3) feet into the firer bedrock stratum may be designed for a maxinun allowable end bearing pressure of thirty recorn:end that all fill in building and pavement areas be placed in horizontal six (6) to eight (2) inch lifts at two percent (24%) wet of optimum moisture content and ccrpacted to a ninimur, of ninety-five ;percent (95%) of Standard Proctor Tensity ASi,i C. 6920-72. Fill placed in proposed greenbelt areas should be compacted to a minirun of ninety percent (90A) of Standard Proctor Density AST 0 0592-79. Where fill is placed on slopes greater than 4:1, horizontal benches should be cut in the slopes to insure integrity of the new fill on the existing slopes. For stability, we recomnend that all cut and fill slopes be no steeper than 2:1; however, flatter slopes are suggested for ease of maintenance. Finished slopes should be seeded with native grasses to ?inimize erosion. All utility trenches extending four (4) feet or acre into the upper soils should be excavated an slopes no steeper than 1:1. The bedrock may be excavated on vertical slopes. Excavation of the bedrock may require the use of heavy-duty construction equipment. Where utilities are excavated below groundwater, dewatering will be required during placement of pipe and backfilling to insure proper construction. All piping should be bedded to insure proper load distribution and to elim- inate breakage during the backfilling operations. nackfill placed in utility trenches in open and planted areas should be compacted in uniform lifts at optimum moisture to at least ninety percent (90:) of Standard Proctor tensity ASTA D 69E-78 the full depth of the trench. The upper four (4) feet of backfill placed in utility trenches under roadways and paved areas should be compacted at or near optimum moisture to at least ninety-five percent (95x) of Stand- ard Proctor Density ASTM D 698-73, and the lower portion of thesi trenches should be compacted to at least ninety percent (90:) of Standard Proctor Density ASTM D 693-78. Addition of moisture to and/or drying of the subsoils nay be required to assure proper compaction. Proper placement of the bedrock as backfill ray be difficult, as is discussed above. Qualified geotechnical personnel should be present during all phases of earthwork to observe stripping of the topsoil. scarification of the subgrade, and placment and compaction of fill. in -place density I - 5- one-half (10-1/2) to sixteen (16) feet below present grades. No water was encountered in the remaining test borings at the j time of this investigation. Groundwater levels at the site will fluctuate with seasonal variations and conditions. ANALYSIS AUD AECOMIENDATIONS We understand that the Neighborhood Center will be developed for commercial use. The proposed buildings will be one- or two -stories with conventional slab -on -grade construction. A basement is proposed for the building to be constructed at the southwest corner of the site. The following are our recommendations for development of the site as influenced by the subsurface conditions encountered in the test borings. Site Grading We anticipate that some cutting and filling will be required on the site to achieve desired finished grades. As building foundations and/or slabs on grade may be supported on fill, we recommend that fill place- ment be in accordance with FNA "Data Sheet 79G." The following are our recommendations for site grading and placement of compacted fill. The upper six (6) inches of all topsoil should be stripped in proposed cut and fill areas and in building and pavement areas which will remain at present grades. The topsoil can be stockpiled on the site and used.fnr final grading outside of building .and pavement areas. At cut subgrade elevation and in areas to receive fill. the upper six (6) inches of the subgrade should be scarified and recompacted at two percent (2110) wet of optimum moisture content to a minimum of ninety percent (90:) of Standard Proctor Density ASIM D 699-78. .(See Appendix i C.) iThe on -site overburden materials are suitable for use as fill in proposed building and pavement areas. Any additional off -site fill required should be a material approved by the geotechnical engineer. We (1) Topsoil and Fill: Thickness of topsoil at test boring lo- cations varies fro;., approximately six (6) to twelve (12) inches. The upper six (o) inches of the topsoil have been penetrated by root growth and organic matter and are not suitable for foundation bearing or as backfill Material. Fill was encountered in Sorings 23, 24, 299 3G. and 33 extending to depths one (1) to t:Ko (2) feet below present grades. The fill is primarily sandy silty clay with some fine gravel. The fill is not suitable for support of foundations. (2) Sandy Silty Clay: The topsoil and fill are underlain by brown, tan and red sandy silty clay extending to the bedrock surface or the depths explored. Some fine gravel and seams and layers of silty sand and gravel were encountered within the sandy silty clay. The primary layers of silty sand and gravel are identified on the Log of Borings. The near -surface portions of the sandy silty clay are medium stiff to stiff and have moderate shear strength and bearing characteristics. With increased penetration into the sandy silty clay, the material becomes more moist and softer. The near -surface portions of the sandy silty clay also exhibit moderate swell potential upon wetting. -_(3) Siltstone-Sandstone Bedrock: The surface of interbedded silt - stone and sandstone bedrock was encountered in Borings 1, 80 14l 209 229 23, and 23 at depths seven and one-half (7-1/2) to twenty-nine and one-half (29-1/2) feet below present grades. The upper one-half (1/2) to two (2) feet of the bedrock for- mation is weathered. T:e underlying interbedded siltstone and sandstone is firm and has good shear strength and bearing characteristics. (4) Groundwater: Water was encountered in Borings 1 through 4, 8, 111, 129 149 1So 139 20 through 22, and 28 at depths ten and SIT^ LOCATION ANC DESCRIPTION The project site is located on the north side of Harmony Road t,c of icMurray Avenue, southeast of Fort Collins, Colorado. More specir cally, the site is situate in the southeast 1/4 of Section 31, Townsi 7 Borth, Mange 69 'dest of the Sixth Prime 'Meridian, Larimer County, Colorado. The project site is presently an open, grass- and weed -covered field. Slope and drainage are positive to the south. An earth ben, been constructed along the south property line adjacent to Harmony is Fill has been end dumped on portions of the site and small irrigatiGr ditches across the property have been filled in. McMurray Avenue, t- the east of the site, has been paved. Property to the north is pre- sently being developed for residential use. Open fields exist to ti west of the site. LABORATORY TESTS AND EXA.-iINATIOA Representative samples recovered in the test borings were selec' for tests in the laboratory to determine their physical characterise- and engineering properties. Included in the test program Were natur_ ;moisture content, water soluble sulfates, Atterberg limits, dry dens- unconfined compressive strength, consolidation characteristics, swell potential, and swell -consolidation characteristics. Laboratory test results are summarized In Appendix B. Hveem stabilometer tests are also being performed for desi;n of pavement sections. The results -of the Hveem tests will be subnitted! upon completion. SOIL AND GRCLSIDWATER CONDITIONS The following are the characteristics of the primary soil strata encountered at the site. - 2- V i REPORT OF d GEOTECHNICAL INVESTIGATION SCOPE This report presents the results of a geotechnical investigation prepared for the proposed Golden Meadows Neighborhood Center, Larimer County, Colorado. The investigation included test borings, laborator; testing, engineering evaluation, and preparation of this report. The purposes of the investigation were to determine subsurface conditions at the site and to provide recomendations for development the site as influenced by the subsurface conditions. SITE INVESTIGATION Thirty-four (34) test borings were drilled at the site on october 1, 2, and 3, 1980. Locations of the test borings are shown on the TLC Boring Location Plan included in Appendix A. The borings were advanced with continuous -flight augers to depths_ seven (7) to thirty-four (34) feet below present grades. Samples werE recovered with .two and one-half. (2-1/2) inch Shelby tubes and the star: and penetration sample technique. During drilling, a field engineer c. Empire Laboratories. Inc. was present and made a continuous visual inspection of soils encountered. Logs prepared from the 'field notes a Included in Appendix A of this report. Indicated on the togs .are the primary strata encountered, locations of sanples, and groundwater con- ditions. -1- V TABLE OF CONTENTS Table of Contents .............................................. Letter of Transmittal .......................................... Report......................................................... Appendix A ..................................................... Test Boring Location Plan .................................... Key to Borings ............................................... Log of Borings ..................:............... ............. Appendix B..................................................... Consolidation Test Data ...................................... Summary of Test Results ...................................... Appendix C..................................................... REPORT OF A GEOTECHNICAL INVESTIGATION FOR ZVFK, ARCHITECTS/PLANNERS FORT COLLINSs COLORADO PROJECT NO. 4213-80 RE: GOLDEN MEADNS NEIGHBORHOOD CENTER LARIMER COUNTY, COLORADO BY EMPIRE LABORATORIES, INC. 214 NORTH HOWES STREET FORT COLLINS* COLORADO 80521 1